House Speaker Kevin McCarthy unilaterally gave his conference the green light to launch an impeachment inquiry into President Joe Biden. Now the harder work begins.

The pressure is on for House Republicans to use the spotlight McCarthy gave them to produce evidence of wrongdoing by Biden -- which they have yet to prove -- that gets even the party's most vulnerable members on board with their impeachment push. That buy-in will be crucial if they want to avoid political backlash and secure the votes for impeachment articles, which is the direction many Republicans believe they are headed.

"There has to be an aha moment." Rep. Darrell Issa of California, a Republican member of the House Judiciary Committee, told CNN. "We certainly see what one might fairly call bribes or unfair enrichment by Hunter Biden. But the actual participation by the vice president and now president -- that still has to be discovered and or nailed down, either for direct participation or knowing participation or receipt of funds."

Issa, a former House Oversight Committee chairman, added: "Nobody's asserting that any of those three are ready. If they were, then articles of impeachment would contain those already."

But there are already disagreements over how to make an "aha moment" happen. Among the key decisions still being weighed: How quickly to issue subpoenas, the length of their inquiry and whether it can have a formal vote to officially authorize their effort, according to multiple lawmakers and aides involved in the discussions. Strategy sessions are already underway, with key committee chairmen planning for their first hearings and delivering briefings to both House and Senate Republicans -- and even scheduling one-on-ones with some of the party's staunchest skeptics.

House Judiciary Chairman Jim Jordan, an Ohio Republican who told reporters he signed three new subpoenas on Wednesday, said the launch of the inquiry does not change how he is approaching his investigation. He doesn't have a specific timeline of how long an inquiry will last, and his plan is simply to "keep going."

"We're just going to continue to do our work, but we think that as we enter this phase, it helps us in court if we have to go to court," Jordan said.

The conundrum now for Republicans is that if they don't convince their colleagues to pursue articles of impeachment and come up short in proving high crimes and misdemeanors, they will essentially be absolving the president leading into an election year. And even if they do succeed in impeaching Biden, making him the fourth US president to ever be impeached, it would be dead on arrival in the Senate -- and could seek to have the adverse effect of rallying Democrats around a president who has faced sagging approval ratings.

"Well, it certainly didn't help Democrats. I haven't seen anybody do too well after an impeachment process. It didn't do well for us in '98 with President Clinton," veteran Rep. Tom Cole, a member of the GOP leadership team, told CNN. "I don't see it as good politics, I do think though that there's enough stuff here that it deserves to be looked at. And I think the speaker had it right when he said this is the next logical step."

Decisions facing the 3 committees leading the impeachment inquiry

The three House committees McCarthy tapped to lead the inquiry, Judiciary, Oversight, and Ways and Means, have been coordinating and communicating for months, but now have a number of key decisions to make.

One of the major questions is how long an inquiry will last. Some lawmakers want to move slowly and build a thorough case that will earn buy-in from across the conference -- and the public.

"What we're going to do is do it the right way," GOP Rep. Kat Cammack of Florida told CNN. "We want to make sure that we have every single piece of evidence."

Asked whether their inquiry should be wrapped up before the end of the year, GOP Rep. Brian Mast, also of Florida, told CNN: "Can it be yes? Should there be an artificial timeline placed on wrapping this up by the end of the year? Absolutely not."

But others in the party want to move quicker, ideally wrapping the inquiry up by the end of the year.

GOP Rep. Dan Newhouse of Washington, one of 10 Republicans to vote to impeach former President Donald Trump for inciting an insurrection, told CNN, "Hopefully it won't last that long. I don't want to see this drag out forever. Just for expediency so you know we can move on to other things."

Said GOP Rep. Tim Burchett of Tennessee: "I think we could do it all in a week, do the inquiry and hold the vote if we have enough to vote to do it, send it to Judiciary and let Jim Jordan's committee handle it."

If House Republicans don't move fast enough, conservative hardliners -- already growing antsy and threatening McCarthy's speakership -- are vowing to force up-or-down votes on impeachment articles, forcing every member on the record over the issue, which GOP leadership says is premature.

"Frankly, my concern is the lack of an inevitability there. We've seen a history with Kevin McCarthy, where when his own power is jeopardized he gaslights an impeachment that will never be," said hardliner Rep. Matt Gaetz of Florida, who serves on the Judiciary Committee. "I think Joe Biden deserves impeachment. No question about that. We may be forcing some votes on it in the coming days and weeks."

Part of the disagreements over how long the inquiry should last stems from whether -- and when -- the House should pursue subpoenas of key witnesses like Hunter Biden or the president's brother, James Biden.

Some view the president's son as a waste of time.

"Hunter Biden is an example of somebody you don't arbitrarily bring in early," Issa told CNN, pointing out that given the ongoing criminal probe into him, the president's son will likely plead the Fifth Amendment to every question asked of him.

Others, though, say that a Hunter Biden subpoena can't come soon enough.

"Today," GOP Rep. Scott Perry of Pennsylvania said, when asked how soon the committees should subpoena Hunter Biden.

The House Oversight Committee is currently weighing whether to subpoena Hunter Biden for bank records, a source told CNN, and would consider a separate subpoena for his testimony further down the road.

"The Oversight Committee will soon pursue Hunter and James Biden's personal and business bank records. The committee also plans to interview additional Biden family associates," a committee spokesperson told CNN.

The risk of going after business records and testimony that pierce the president's inner circle is matters can get tied up in court.

"You never know," Jordan said about the risks of going to court. "That seems normally how these things play out, but we hope not."

Comer said he plans on holding a hearing in September to summarize his committee's findings and that he wants to interview people who have knowledge of Hunter Biden's business dealings.

"We are following the money and we'll see where that leads," he told reporters on Wednesday.

With the launch of the inquiry, the roles of each committee have been more clearly defined. House Oversight Chairman James Comer of Kentucky will focus his work on the Biden family and their finances, Jordan will lead his panel on the alleged cover up and House Ways and Means Chairman Jason Smith of Missouri and his committee will continue to address tax sensitive information.

The panels have already been working in close coordination. They've sent multiple letters as a group, the chairs communicate constantly, and counsel for the House Judiciary Committee is also detailed to the House Ways and Means panel, two sources told CNN. McCarthy's chief of staff and general counsel are also helping to run point and coordinate among the three committees, according to a GOP source.

McCarthy has faced criticism for bypassing a floor vote and directing his committees to move ahead, since he criticized Democrats for initially doing the same during their first impeachment of Donald Trump. The speaker's decision came as he was facing pressure from the right to move ahead but did not yet have 218 votes to launch an inquiry.

"I never changed my position," McCarthy said Wednesday, adding he can "easily" justify proceeding with an impeachment inquiry without holding a floor vote because former House Speaker Nancy Pelosi did the same thing in 2019 when she tapped House Democrats to open an inquiry into former President Donald Trump.

But leadership is leaving the door open to eventually holding a floor vote on their inquiry and believe the votes will be there as they work to build more buy-in from members over the next month.

Asked whether an inquiry vote was still on the table, Rep. Mike Johnson, a member of the Judiciary panel and the GOP leadership team, said: "Oh, it definitely is. Yeah."

'I want to hear clarity'

In the more immediate term, the committees are focused on communicating to their colleagues what they have already uncovered -- part of an effort to justify why the inquiry was necessary -- and where they see it headed.

House Republicans are slated to hold a special conference meeting on Thursday morning in the Capitol dedicated solely to the subject.

"I want to hear clarity as to what got us to this point, so that I feel good about moving forward in this direction," Newhouse told CNN. "And the plan for in a timely manner being able to proceed with the inquiry or get the information that we need in order to make decisions."

Meanwhile, Comer and Jordan trekked across the Capitol on Wednesday to brief Senate Republicans, who have so far shown little appetite for the House GOP's impeachment push.

Senate Republican whip John Thune of South Dakota said of the presentation, "There's enough smoke there," but he warned some of the records Comer and Jordan are seeking they may not ever get.

"There are legitimate questions that they need to get answers to which they probably aren't going to get because they ... get stonewalled on a lot of the information they need."

Sen. Lindsey Graham of South Carolina said the chairmen's presentation was "compelling."

"I don't know where it ends. I think they should eventually take a vote on impeachment inquiry, but I think any reasonable person listening what they found would be impressed," Graham said.

There's also an effort to give one-one-one briefings to certain holdouts. GOP Rep. Ken Buck of Colorado, who has been a vocal skeptic of impeachment, is scheduled to receive a briefing from House Oversight Committee staffers on Friday, which was arranged by leadership and first reported by CNN.

So far, Buck is not changing his tune, though he says he is open to seeing whatever evidence they have.

"I haven't seen evidence linking Hunter Biden's activities to Joe Biden," Buck told reporters Wednesday. "Until I see the evidence of an impeachable offense, I'm not in favor of impeachment inquiry or impeachment."

Some moderates in swing districts, though, are expressing support for the impeachment inquiry, and dismissing concerns that it could negatively impact the GOP.

"This is good government, it's good politics," Rep. Nick LaLota of New York, a Republican in a Biden-won district, told CNN. "And if we keep it on the facts, and don't allow it to become political, and some things inevitably always become so, but if we keep it to the fact as to how these payments affect or didn't affect national security, I think my constituents will want me to continue down this path."

But whether moderates will be on board with impeachment articles is a separate question. Some House Republicans cautioned that an impeachment inquiry does not make articles of impeachment inevitable.

"I believe that the evidence is very strong," Johnson said. "But we have to keep an open mind through the inquiry and finish the investigation."

But others argued impeachment was likely a foregone conclusion.

"Where there's smoke, there's fire. There's a hell of a lot of smoke here, you can even say there's a few flames," Mast said. "So yeah, I think it's absolutely headed in that direction."