It was an excruciating moment of powerlessness for one of Washington's most powerful men.

Senate Minority Leader Mitch McConnell's words dried up and he froze, standing silent and staring straight ahead for around 30 painful seconds in the middle of a press conference Wednesday -- the second time he had endured such an uncomfortable on-camera ordeal since July. It is not clear whether it has happened more times away from the public's gaze. But for a proud senator who has dominated the chamber for many years, the momentary loss of lucidity is embarrassing at the very least, and could become an increasing political problem.

The 81-year-old Kentucky Republican was able to resume his remarks, haltingly answering a question on the commonwealth's gubernatorial race, and later attended a fundraiser for a Senate candidate. But his misfortune immediately revived questions about his health and age -- especially since he suffered a concussion in a fall earlier this year. His office insisted Wednesday that the veteran senator had simply been feeling "momentarily lightheaded."

More broadly, Wednesday's events threw the spotlight back onto one of the defining trends in today's US politics: the senior citizens who have no intention of leaving posts atop the US government, including 80-year-old President Joe Biden, and one former president who wants power back -- 77-year-old Donald Trump. Also in the Senate, California's Dianne Feinstein, 90, has been ill and displayed apparent cognitive decline in public in recent months.

The issue of whether someone is too old to serve is a discomforting one, since it involves discussing private health issues and mortality. And in the case of Feinstein, some have complained that demands for her to leave her job are sexist since plenty of aging male senators -- like the late Strom Thurmond of South Carolina, who was 99 when he retired from the chamber, and the late Robert Byrd of West Virginia, who was 92 when he died in office in 2010 -- didn't face similar demands to step down.

But given that Biden, McConnell and Feinstein are public officials, voters are entitled to a high level of transparency.

Dr. Jonathan Reiner, a cardiologist and professor George Washington University, told CNN's Erica Hill Wednesday that his heart went out to McConnell, but that the senator's position means that he owes his constituents details about his health.

"The senator is really the principal member of his caucus in a very tightly held United States Senate and concerns about his health really resonate with the public, so I think they should be a little bit more transparent about where he is right now," said Reiner, also a CNN medical analyst.

The age issue Biden will be unable to dodge

The higher the job, the more important transparency becomes. Biden, for instance, would be 86 by the time his second term ends, which represents his biggest vulnerability in the 2024 election.

An Associated Press-NORC survey released this week found that 77% of Americans think Biden is too old to be effective for four more years. Remarkably, in an age where major questions divide on party lines, 69% of Democrats shared that view. Only about half of US adults, however, said that Trump was too old to be effective -- even though he would be well into his 80s by the end of the non-consecutive second term he is trying to win next year. Trump's frenetic behavior and often unhinged public appearances seem somehow to obscure questions about his age.

Republicans and conservative media outlets drive a constant narrative that Biden is confused, old and senile. Episodes like the time he fell off his bike in Rehoboth Beach, Delaware, only played into this critique and made the president an object of ridicule on the right.

The struggle that White House press secretary Karine Jean-Pierre had in navigating the issue in an interview with CNN's Jake Tapper this week illustrated just how difficult it will be in the campaign. Tapper told Jean-Pierre that she was diverting the conversation to Biden's record while he wanted her to respond to questions about the president's "age and stamina" and the way he had aged in perhaps the world's most demanding job. Jean-Pierre pointed out Biden's visit to the war zone in Ukraine earlier this year and claimed that some much younger reporters in the White House press corps had trouble keeping up with the president.

Biden is in generally good health, and his doctors say that he is fit for duty. But his age and acuity is already an issue in the 2024 campaign. Former South Carolina Gov. Nikki Haley, for instance, is proposing a mental competency test for politicians over the age of 75 as she beseeches Americans in her GOP primary campaign to embrace a new generation of leadership. Her scheme would not just involve Biden; it would also conveniently ensnare the GOP front-runner -- Trump.

Haley is also among the first Republicans to coin a line that will be heard frequently next year -- that a Biden second term would increase the likelihood that unpopular Vice President Kamala Harris, who is a heartbeat away from the presidency, gets the top job. "I think that we can all be very clear and say with a matter of fact that if you vote for Joe Biden, you really are counting on a President Harris, because the idea that he would make it until 86 years old is not something that I think is likely," Haley told Fox News in April, in remarks that seemed in rather poor taste but made a valid political point.

Where are the younger leaders?

In some ways, the age question is a product of societal and medical advances -- people generally live longer now than they did 100 years ago. Seeing older people doing stressful and responsible jobs can inspire admiration.

Yet the age of some key leaders does beg the question whether their refusal to ride into the sunset is thwarting the rise of a new generations of politicians or whether younger figures in both parties lack the talent and the drive to push them aside. Similar questions came up before a generational shift in the Democratic leadership in the House of Representatives after the last election, when longtime Speaker Nancy Pelosi, who is now 83, and her longtime lieutenant, Rep. Steny Hoyer, who is now 84, handed over the reins of leadership. The price for staying in power too long was underscored for many Democrats when Supreme Court Justice Ruth Bader Ginsburg died at the age of 87 in 2020, opening a vacancy that McConnell rushed to fill just before the 2020 election.

But many leaders have spent decades accumulating power and, therefore, may be reluctant to give up everything they've worked for. Biden, for example, spent nearly 50 years in Washington before being elected president, leading some to say he should not be precluded from running for a second term if he's otherwise feeling fine. The Senate's system of seniority means it can take numerous six-year terms for someone to accrue real authority and to win chairmanships of plum committees. As with the presidency, there is a constitutionally mandated minimum age to be in the chamber, but no similar restriction regarding an upper age limit.

It is one thing for a powerful senator to have a scare. The presidency is on another level, however. Should Biden, if he wins a second term, experience a similar moment to McConnell, questions about the continuity of US leadership would reverberate around the world and offer openings for US adversaries.

McConnell seeks to play down incident

McConnell will be under even more scrutiny when the Senate returns to work next week after Labor Day. The titan on Capitol Hill is known for his slow walk -- the legacy of a childhood bout with polio -- but it has been painfully clear recently that his age is showing.

His plight will also increase speculation about whether he plans to remain leader after the 2024 elections, when he hopes to regain the majority, or whether he'll run for reelection two years after that. Even more than after the earlier incident in July, he must now consider what the voters of Kentucky deserve to know about his health.

McConnell moved quickly on Wednesday to stop his episode from evolving into an issue that could threaten his long-held leadership position -- which he has wielded skillfully through successive Republican majorities and minorities. His signature achievement has been to build the conservative majority on the Supreme Court that is likely to long outlive him.

He was soon on the phone after his frozen moment, apparently seeking to minimize political fallout. A spokesperson for Sen. Shelley Moore Capito told CNN's Manu Raju that the West Virginia Republican spoke to McConnell and he "sounded fine." Republican Whip John Thune also chatted with the leader, who "sounded like his usual self and was in good spirits," the South Dakota senator's spokesman said.

An aide said McConnell "feels fine" but would be checked out by a physician before his next event "as a prudential measure." The leader later attended a fundraiser for Rep. Jim Banks' Senate bid, where one source told CNN's Raju the leader was "very dialed in" about the Indiana Republican's campaign.

Being old has hardly ever been a disqualification in the Senate -- a chamber where incumbents typically serve long past most Americans' retirement age. Sprightly Iowa GOP Sen. Chuck Grassley won a new term in 2022 and shows few signs of slowing down at 89. Feinstein's situation, however, shows the possibility that staying in the Senate at an advanced age can create an undignified coda to a great career. The California Democrat has appeared confused at times, disputing the length of her absence and her diagnoses. In a Senate Appropriations Committee hearing at the end of July, Feinstein had to be prompted to vote "aye" by the panel's chair.

Concerns for Feinstein's health grew earlier this year, along with demands for more accountability, after she was hospitalized with shingles. Her long absence from Capitol Hill was also a complication for Democrats given their small Senate majority. In a stunning move, several Democratic members of the House called for Feinstein, who's already said she isn't running for reelection next year, to step down. A fiercely competitive primary is already underway for her seat.

It's hardly the twilight of a political career that Feinstein, a pioneering female politician, would have preferred. But it also highlights the sensitivity of knowing when to quit -- a question McConnell may also soon be forced to confront.