Two Senate Democrats came out in support on Monday of confirming CIA Director Mike Pompeo as the next secretary of State, giving him a jolt of momentum ahead of vote later this afternoon on the Senate Foreign Relations Committee.

Sens. Joe Manchin (D-W.Va.) and Joe Donnelly (D-Ind.) said they would vote for Pompeo, becoming the second and third Democrats to announce their support. Sen. Heidi Heitkamp (D-N.D.) announced her support on Friday.

They would give Pompeo more than enough votes to win approval on the Senate floor, even if he gets another GOP "no" vote.

Sen. Rand Paul (R-Ky.) is the only Republican expected to vote against him, though Sen. John McCain (R-Ariz.), who is battling brain cancer, is almost certain to miss the vote. Sen. Jeff Flake (R-Ariz.) is also undecided on Pompeo.

If the Senate's other 48 Republicans vote "yes," that would give Pompeo 51 votes with the three Democrats.

Sen. Angus King (I-Maine) and three Democratic senators who backed Pompeo's confirmation as CIA director remain on the fence over his confirmation as secretary of State: Claire McCaskill (D-Mo.), Minority Leader Charles Schumer (D-N.Y.) and Mark Warner (D-Va.).

A fourth Democratic senator who supported Pompeo for CIA director, Maggie Hassan (N.H.), came out in opposition to Pompeo's nomination following the endorsements from Manchin and Donnelly.

Manchin, who like Donnelly and Heitkamp faces a challenging reelection race this fall in a state won by Trump in 2016 by double digits, noted Pompeo's "exemplary" career in offering his support.

"After meeting with Mike Pompeo, discussing his foreign policy perspectives, & considering his distinguished time as CIA Director & his exemplary career in public service, I will vote to confirm Mike Pompeo to be our next Secretary of State," Manchin said in a tweet.

Later on Monday, Donnelly also announced his support.

"We need a Secretary of State who will give the president an honest assessment on critical issues, including Russia, Syria, and the defeat of [the Islamic State in Iraq and Syria] ISIS. I believe Director Pompeo is capable of advancing U.S. interests and leading the State Department," Donnelly said in a statement.

Before Pompeo's nomination gets to the floor, he faces a possible historic defeat at the Senate Foreign Relations Committee.

Pompeo is expected to fail to receive a favorable recommendation from the panel during a vote scheduled for early Monday evening, where Republicans hold a one-seat majority on the committee. Paul is a member of the committee and no Democrats on the panel are supporting Pompeo.

Sen. Bob Corker (R-Tenn.), chairman of the Foreign Relations Committee, could either send his nomination to the floor with an unfavorable recommendation or no recommendation.

Senate Majority Leader Mitch McConnell (R-Ky.) could also try to discharge the nomination from committee, but that gives Democrats the leverage to potentially filibuster Pompeo because the move would require 60 votes.

This story was updated at 2:23 p.m.