By Phil Mattingly, CNN

(CNN) -- President Donald Trump's pick to be secretary of state faces a key committee vote Monday evening, where Mike Pompeo is not expected to have enough support for a favorable recommendation, a distinction not seen before in recorded US history for a nominee to be the nation's top diplomat.

While Pompeo can still -- and is expected to -- advance for a full floor vote, where his supporters believe he'll be able to advance, in the Senate Foreign Relations Committee, the numbers on the panel are against him. Of the committee's 21 members, all 10 Democrats plus one Republican, Sen. Rand Paul of Kentucky, have said they'll vote against him. That puts Pompeo in line for a historic distinction: the first secretary of state nominee not to win a favorable recommendation from the committee, according to the Senate Historian's office.

Keep an eye on this piece of protocol: the committee technically has to approve sending the nomination to the floor unfavorably.

That means if all who are opposed to the nomination are opposed to sending it to the floor at all, even unfavorably, Pompeo has a really big problem. This has been discussed among some Democrats, however, aides say that as of this point, almost certainly will not occur.

There's a difference between voting against a nominee and blocking other, non-committee senators from their own vote on the floor, the aides point out. Several senior Democratic aides CNN has spoken to say it's unlikely that path will be pursued.

Trump tweeted about the opposition Pompeo in the hours before his vote.

"Hard to believe Obstructionists May vote against Mike Pompeo for Secretary of State. The Dems will not approve hundreds of good people, including the Ambassador to Germany. They are maxing out the time on approval process for all, never happened before. Need more Republicans!" Trump tweeted.

Democrats, for their part, have raised concerns with what they view as Pompeo's hawkish posture on foreign policy and lack of willingness to stand up to Trump, who has a well documented close relationship with the current CIA chief.

But Republicans have countered that the opposition is driven far more by Democratic dislike for the President than the nominee himself. Pompeo, a former congressman who graduated first in his class from the US military academy and received a degree from Harvard law, has moved into a central role in the Trump administration's negotiations with North Korea, secretly meeting with the country's reclusive leader Kim Jong Un earlier in the month. It's something supporters have touted as another example of why Pompeo is ready for the job as the country's top diplomat.

As for the full Senate vote, senior GOP aides are comfortable with Pompeo's floor vote at the moment. Sen. Heidi Heitkamp, a North Dakota Democrat, is a "yes," which means he'd have the votes if all other Republicans -- minus Paul -- vote in favor. Sen. Joe Manchin, a West Virginia Democrat, tweeted that he'd support Pompeo as well.

That means even if Sen. Jeff Flake, an Arizona Republican who has voiced concerns about Pompeo, ends up voting no, Pompeo should still be able to win confirmation.

There is one other current undecided Democrat expected to vote yes, per GOP and Democratic aides: Sen. Joe Donnelly of Indiana, who is facing re-election this year in a state Trump won. There are two other current undecided senators who caucus with the Democrats and who are viewed as on the fence and possible yes votes: Sen. Doug Jones of Alabama and Sen. Angus King of Maine.