President Joe Biden weighed in for the first time on the ouster of McCarthy, calling on Congress to change the "poisonous atmosphere in Washington" and come together.

"More than anything we need to change the poisonous atmosphere in Washington. You know, we have strong disagreements, but we need to stop seeing each other as enemies. We need to talk to one another, listen to one another, work with one another. And we can do that," Biden urged while delivering remarks on student loans at the White House.

Biden said the GOP will need to "reorganize" and that it might "take some time" to select a new leader.

-ABC's Justin Gomez and Molly Nagle

House Majority Leader Steve Scalise has officially entered the race to replace McCarthy.

The Louisiana Republican, in a lengthy letter to his colleagues on Wednesday, made a pitch for unity as he touted his work as the No. 2 House Republican.

"You know my leadership style I've displayed as your Majority Leader and Whip," he wrote. "I have a proven track record of bringing together the diverse array of viewpoints within our Conference to build consensus where others thought it impossible."

"Our strength as a Conference comes from our unity, and we have seen when we unite as a Conference, we can deliver wins for the American people," he wrote. "Now we need to take those unified positions and work to extract conservative wins from the Democrat Senate and White House by leveraging upcoming deadlines. While we need to be realistic about what can be achieved, if we stay united, we can preserve leverage for the House to secure tangible wins in our impending policy fights."

Rep. Jim Jordan has sent a letter to colleagues announcing his speakership bid.

"We are at a critical crossroad in our nation's history," he wrote. "Now is the time for our Republican conference to come together to keep our promises to Americans."

Senate Republican leader Mitch McConnell said he is keenly aware of the thankless work it takes to be a Congressional leader as he praised McCarthy in a floor speech.

“I’ve said before, in reference to my own position, that being the leader of your party in the Senate is much like being the groundskeeper at a cemetery. Everybody’s under you, but no one’s listening," McConnell said, adding: “Of course, I doubt that Kevin McCarthy has ever seen himself as above anyone else."

McConnell praised McCarthy's willingness to dive "head first" into worthwhile fights, calling him a trusted and honest partner in leading the GOP caucus.

“He didn’t hesitate to get his hands dirty. When circumstances were tough, he drew on his faith, his family and his belief in American exceptionalism," McConnell said.

“And I’m not sure anyone could have predicted just how much these qualities would come in handy over the past nine months," he said.

-ABC's Mariam Khan

From the moment McCarthy was elected speaker, it was clear that his ability to keep that job could depend on Democrats.

To get elected on that 15th ballot in January, McCarthy had to agree to a series of rules that made him a profoundly weak speaker -- including the provision allowing a single member of the House to call for a vote to oust him (the now-famous "motion to vacate"). But while it takes just one member to call for such a vote, it requires a majority to actually remove the speaker.

McCarthy could survive a rebellion from a handful of renegade Republicans -- but he could not survive such a rebellion if Democrats go along with it.

Gaetz has said he expected Democrats to save McCarthy. Many others did too.

As recently as Tuesday morning, House Minority Leader Hakeem Jeffries suggested a way out of this for McCarthy. In an interview on MSNBC, he said House rules should be changed so that a single member could not force a vote on removing the speaker. Jeffries could deliver the votes to save McCarthy's job and the votes to change the rules to make it impossible for Gaetz to pull off a stunt like this again.

But Democrats would have a price for doing that. What would McCarthy offer in return? An end to the impeachment inquiry in President Joe Biden and his family? A guarantee that McCarthy honors the deal he struck on spending with the White House? Power sharing?

McCarthy has developed a cordial relationship with Jeffries, but he signaled no willingness to give Democrats anything in exchange for keeping the job.

In fact, McCarthy's actions have made it virtually impossible for Jeffries to throw him a lifeline. The speaker unilaterally launched the impeachment inquiry and just Saturday infuriated Jeffries by attempting to jam Democrats on a bill to keep the government funded for 45 days.

Back in January -- and again last month on impeachment -- McCarthy showed he was willing to do almost anything to appease his right-wing critics to get and keep his job. That worked for a while -- but it has made it virtually impossible to get Democrats to save him now.

-ABC News Chief Washington Correspondent Jonathan Karl