Much remains unknown of course about the presidential general election whose traditional kick-off will come one year from today on Labor Day, 2024.

But one thing is already clear: the race will almost certainly be decided by a handful of voters in the very few states not entirely secure for either party.

The roster of swing states that both sides can genuinely hope to win may be as small next year as at any point in modern history -- no more than seven or eight and perhaps as few as four. On such a concentrated battlefield, the margin between success and failure for the two parties may be achingly narrow and the competition for voters fiercely intense.

"Never have so few people had such a big impact in deciding the future of American politics," said Doug Sosnik who served as the chief White House political adviser for Bill Clinton.

Multiple measures track the evolution of what could be called the incredible shrinking presidential battlefield.

The most revealing is the growing number of states where either party has established a consistent advantage in the presidential race. Twenty states have voted for the Democratic nominee in each of the past four presidential elections, from Barack Obama's first win in 2008 through Joe Biden's victory in 2020. Twenty states have likewise voted for the GOP presidential nominee in all four of those contests.

That means 40 of the 50 states, or 80%, have voted the same way in four consecutive presidential elections. That's the highest level of such consistency since the turn of the 20th century. Even when Franklin D. Roosevelt won four consecutive elections from 1932 through 1944, only about two-thirds of the states voted the same way each time. Just under three-fourths of the states voted the same way in the four consecutive Republican presidential victories from 1896 to 1908. From 1976 through 1988, only half the states voted the same way each time.

And while it's striking enough that just 10 states have flipped between the parties at any point since 2008, even many of those are not considered real swing states at this point: that list includes Indiana, Iowa, Ohio and Florida, which have all voted solidly Republican in the Trump era. North Carolina, another of the 10 switchers, hasn't moved as definitively, but has tilted reliably red in federal elections since Obama won it in 2008.

Kyle Kondik, managing editor of Sabato's Crystal Ball, published by the University of Virginia's Center for Politics, points to another measure of the contracting battlefield. In the razor-thin presidential elections of 1960 and 1976, he points out, states awarding about 70% of the total Electoral College votes were relatively competitive each time, by which he means that the margin of victory in them for either side was within four percentage points of the overall national popular vote.

In the presidential elections of 2012, 2016 and 2020, though, the states where the margin of victory landed within four points of the national vote total dwindled. Over those three elections, Kondik said, such competitive states accounted for less than one-third of all Electoral College votes. "We are in this era of close presidential general elections, but not that many close states," he said.

These changes will most likely leave the two sides scrapping over a very small list of battleground states next year. The Crystal Ball publication recently tabbed only four states as genuine tossups for 2024, while identifying four others as "leaning" states that favored one side but might still fall to the other. The non-partisan Cook Political Report with Amy Walter identified four states as toss-ups and three as leaners.

Both of these analysts, as well as Sosnik, identify the same states as potentially the most competitive, though they differ slightly in how they rank them. Generally, all the analysts agree that Arizona, Georgia and Wisconsin, three states that flipped from Trump in 2016 to Biden in 2020, remain toss ups. They also agree that Michigan, Nevada, and Pennsylvania, which Biden won, and North Carolina, which backed Trump, are likely to remain at least somewhat competitive. One difference is that the Crystal Ball identified Nevada as the fourth toss-up and categorized Pennsylvania as leaning toward the Democrats, while the Cook team reversed those designations. Another is that the Crystal Ball team, as well as Sosnik, put New Hampshire on the list of states that lean Democratic, while Cook considers it more safely blue.

After the results in the 2022 election, my own judgment is that the list of true swing states entirely within reach for either side may dwindle to no more than Arizona, Georgia, Nevada and Wisconsin.

Anyone who can actually win the GOP nomination would likely be too conservative, especially on social issues, to win New Hampshire. And while any Republican nominee would surely try to keep Michigan and Pennsylvania in play next year, that may not be easy.

The key to Trump's winning the White House in 2016 was his success in dislodging Michigan and Pennsylvania, as well as Wisconsin, from what I termed the "blue wall": the 18 states that voted Democratic in all six presidential elections from 1992 through 2012. But since Trump's initial breakthrough, Democrats have regained ground in all three of those Rustbelt states, with Biden recapturing each in 2020 and the party winning their gubernatorial elections in 2018 and 2022.

Democrats won the governorship in all three states last year by margins that far exceeded Biden's 2020 totals, posting especially strong performances in the white-collar suburbs that have proven the most resistant to the Trump-era GOP. That success was especially striking because it came despite exit polls showing that most voters were negative on both the economy and Biden's job performance. Democrats overcame those headwinds to win decisively in the Michigan and Pennsylvania gubernatorial contests (as well as a Pennsylvania Senate race) largely behind preponderant support from the large majority of voters in each state who wanted abortion to remain legal. Those results underscored how difficult it may be for the GOP to retake Michigan and Pennsylvania while abortion rights remain front and center for voters.

Wisconsin is an inherently closer state than those two; Democrats won the governor's race last year by a much smaller margin than in Michigan or Pennsylvania and Republican Sen. Ron Johnson narrowly won reelection there. But the landslide win this spring for a Democratic state Supreme Court justice in a race that revolved around abortion rights suggests that even Wisconsin may now tilt somewhat Democratic while that issue is so prominent.

Conversely, Democrats are hoping that the move by the Republican-controlled state legislature to impose an unpopular abortion ban in North Carolina over the veto of Democratic Gov. Roy Cooper might allow the party to reverse its decline there since Obama's breakthrough win in 2008. But Democrats have not built the sort of voter mobilization infrastructure in the state that has propelled their advance in Georgia and Arizona and most in both parties believe it remains an uphill (though not inconceivable) climb for them in 2024.

With so few states truly in play, the amount of advertising aimed at voters within them through every conceivable medium will likely be overwhelming. "You won't be able to escape it," said Erika Franklin Fowler, co-director of the Wesleyan Media Project at Wesleyan University. "I'd be hard pressed to put a number on it, but the citizens there no matter what screen they are on -- whether they are on a mobile device, tablet, television, gas pump -- they will be seeing ads everywhere."

This early ranking of the states has momentous, but somewhat contradictory, implications. The most obvious is that if it holds, Democrats would start much closer than Republicans to the 270 Electoral College votes required to win the presidency. If the GOP can't reverse the recent movement of Michigan and Pennsylvania back toward the Democrats, "then it's a real narrow path for the Republicans," as Kondik says.

That's apparent when considering one scenario Democrats often discuss when looking to next year. Of the 20 states that have voted Democratic in at least the past four presidential elections, Nevada is the one that seems most within risk of tipping toward the GOP. But even if Republicans peel away Nevada next year, holding Michigan and Pennsylvania would allow Biden to reach at least 270 Electoral College votes if he captures any of Arizona, Georgia or Wisconsin. (The asterisk is that to reach 270 while winning only Wisconsin would also require Biden to hold the Democratic-leaning second Congressional District in Nebraska, one of the two states that awards some of its Electoral College votes by district.) Put another way, the eventual GOP nominee will likely be operating with a smaller margin for error in 2024 than Biden will.

Yet this shrinking map could also have the paradoxical effect of allowing the campaigns to at least test the waters in more states than in 2020.

One of the most striking aspects of these early forecasts is that Ohio and Florida are conspicuously absent from the states considered competitive.

It's difficult to identify another presidential election since World War II when Florida or Ohio, or both, were not among the most fiercely contested battlegrounds. Florida famously decided George W. Bush's win in 2000, and Ohio cemented his victory in 2004. As recently as 2016, Hillary Rodham Clinton spent more money advertising in those two than any other state; while Biden largely conceded Ohio in 2020, Florida still saw more television advertising than any other state. When former New York City mayor and 2020 Democratic presidential candidate Michael Bloomberg wanted to boost Biden late in the campaign, he announced a $100 million investment in Florida.

The Biden campaign has dipped a toe into Florida, including spots aimed at Hispanics there in its initial television advertising buy (which otherwise is running across the seven states considered most competitive -- Arizona, Georgia, Nevada, and North Carolina in the Sunbelt, and Michigan, Pennsylvania and Wisconsin in the Rustbelt). But Biden aides acknowledge they are far from deciding to mount a full-fledged campaign in Florida, and even key Democratic strategists there agree that given the state's rightward drift over the past decade, the president might better focus his efforts elsewhere. "While I love the attention my state gets, and I've loved being part of two wins here, the fastest way to 270 for Democrats is through the upper Midwest states," said Steve Schale, the lead strategist for Obama's 2008 and 2012 Florida wins.

In the next breath, though, Schale acknowledges the risk for Democrats in entirely writing off Florida: if Republicans don't have to devote any resources to defending the Sunshine state, they will have much more money available to spend elsewhere. The same will be true if Biden effectively concedes Ohio. That could free the GOP to invest beyond the inner circle of most competitive places to states such as Minnesota, New Hampshire, Virginia and Oregon, that clearly lean Democratic, but might not be completely out of reach for Republicans in the right national environment.

One GOP strategist familiar with the Trump camp's thinking said that as the nominee he would likely explore exactly such possibilities. Democrats would have the same chance to spread their money into new places if Ohio and Florida stay off the board, but beyond North Carolina it's difficult to identify another GOP-leaning state that Biden could even remotely hope to contest. (Texas might be his best option and, as the 2022 election results there demonstrated, it's not currently a very good one.)

Eventually a Democratic choice to write off Florida and Ohio could provide a tactical benefit for the GOP presidential nominee. But in the meantime, Biden's early advertising in the battleground states is creating a here-and-now tactical advantage for Democrats. No Republican group is yet responding to Biden's ads, Democrats say. Trump has chosen to channel much of his campaign fund-raising toward his own legal bills, which could reduce his capacity to respond for months if he's the eventual Republican nominee. "Biden is going to tell his economic story in a positive way, and he is going to bash Trump in a negative way and it's going to be a one-sided conversation for months," predicted Democratic pollster Ben Tulchin.

As Fowler and others point out, such advantages in paid advertising historically have mattered less in presidential than down ballot races because voters receive so much information about the candidates through the media. In a Biden-Trump rematch, she notes, opinions might be even more impervious to advertising than in a typical race because voters have such well-established views about each man. But advertising in the presidential contest, Fowler says, still "matters at the margins." And margins may be exactly what decides a presidential general election that, even a year from the traditional 2024 Labor Day kick-off, already looks highly likely to turn on very few voters in very few states.