In remarks about the speakership showdown, Biden said there is a "lot of work" to get done as Congress faces a Nov. 17 deadline to come to a funding deal or once again risk a shutdown.

"We cannot and should not again be faced with an 11th-hour decision, brinksmanship that threatens to shut down the government," Biden said.

He also expressed concern on the current state of future aid for Ukraine, admitting he's worried it may not happen.

"It does worry me," he said. "But I know there are a majority of members of the House and Senate in both parties who have said that they support funding Ukraine."

At least one lawmaker vying for speaker has long been opposed to additional Ukraine aid.

"I'm against that," Rep. Jim Jordan told reporters on Wednesday. "What I understand is at some point we're going to have to deal with this appropriation process in the right way and we're going to try to do that in the next -- what are we down to? Forty-one days. The most pressing issue on the mind of Americans is not Ukraine, it is the border situation."

-ABC's Molly Nagle, Justin Gomez and Mary Bruce

Scalise made his case for why he should be the next House speaker in a letter to colleagues on Wednesday.

In it, he called the Republican conference a "family" as he recounted the support he received when he was shot during congressional baseball practice in 2017 and suffered life-threatening injuries.

"God already gave me another chance at life," he wrote. "I believe we were all put here for a purpose. This next chapter won't be easy, but I know what it takes to fight and I am prepared for the battles that lie ahead."

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."