(CNN) -- Sen. John McCain has yet to say the race for the GOP presidential nomination is over, but some of his colleagues in Congress have already declared him the winner.
Sen. John McCain, standing with Rep. John Boehner, received the endorsement of the GOP House leaders.
McCain, fresh off of three big wins in the so-called Potomac primaries on Tuesday, met with the House Republican leadership behind closed doors Wednesday morning and emerged with their support.
The endorsement from the top Republicans came hours after McCain's camp released a memo saying it's "mathematically impossible for Gov. Huckabee to secure the Republican nomination for president." Former Arkansas Gov. Mike Huckabee is McCain's last remaining competitor for the nomination.
Rep. Roy Blunt, the Republican whip, declared the race over and said McCain would be the best person to help Republicans take back the House. Watch McCain thank GOP leaders »
House Minority Leader John Boehner started off his endorsement by acknowledging how many times McCain and the party have butted heads, but said it was his strong, principled leadership on Iraq that persuaded him to endorse the senator.
"I have watched this presidential race unfold, and I have watched John McCain be a strong advocate for the principles I believe in," he said. "So today I stand before you, proud to endorse my friend, proud to endorse my colleague John McCain, the next president of the United States."
Huckabee insists he's staying in the race, despite the numbers leaning heavily in McCain's favor.
McCain has 827 delegates to Huckabee's 217, according to CNN calculations.
A candidate needs 1,191 to become the Republican nominee.
According to the memo released by McCain's camp, Huckabee would need to win more delegates than remain in the future contests to reach the threshold.
"With only 774 delegates left on the table after tonight, Gov. Huckabee cannot win the Republican nomination for president," the memo says.
Still, Huckabee is marching on. He has plans to spend the next two days in Wisconsin, which holds its primary next Tuesday.
McCain swept the primaries in Maryland, Virginia and the District of Columbia on Tuesday and has largely turned his focus to a national campaign.
McCain on Wednesday said he respects Huckabee's commitment to stay in the race, but he'd prefer if he were no longer in it.
"Of course I'd like for him to withdraw today. It would be much easier, but I respect and have repeatedly said that I respect his right to continue in this race for just as long as he wants to," he said.
Huckabee said McCain was "too much of a gentlemen" to ask him to step aside.
Following his Tuesday losses, the former Baptist preacher said he planned to stay in the race until someone secured the nomination.
"That has not yet happened. We're still continuing to work and to give voters in these states a choice," he said, pledging to give voters in the coming primaries "a solid, conservative, absolute pro-life candidate" as an alternative to McCain.
McCain was also pressed about the three impressive wins in Tuesday's primaries for Illinois Sen. Barack Obama over New York Sen. Hillary Clinton, and what approach he will take to energize Republican voters.
"I congratulate both Sen. Obama and Sen. Clinton for the campaigns they've run. They've gotten the voters engaged. We will do that as well," he said.
McCain, however, said there's "a lot of work to do" and the goal is "reenergize our base, we have to get everybody united." E-mail to a friend
CNN's Dana Bash contributed to this report.