Senate Majority Leader Mitch McConnell (R-Ky.) speaks at the Capitol on Tuesday. (Joshua Roberts/Reuters)

Senate Democrats have created a logjam for President Trump’s executive-branch nominees. But now it’s fellow Republicans who are causing headaches for some of his major Cabinet selections.

With the absence of Sen. John McCain (R-Ariz.) as he battles brain cancer, Senate Majority Leader Mitch McConnell (R-Ky.) begins each confirmation fight knowing that there are, at most, 50 Republican votes he can count on. And already his home-state colleague, Sen. Rand Paul, has jumped out quickly to announce his opposition to Mike Pompeo as secretary of state and Gina Haspel as CIA director to fill Pompeo’s slot.

The other 49 Republican votes aren’t guaranteed, either.

“I have a lot of questions, on both,” Sen. Jeff Flake (R-Ariz.) said Tuesday after his courtesy meeting with Pompeo. He declined to state what those were but added that he is not yet supportive of either nominee. “I raised a couple of issues that I want answers on first,” Flake said.

Gina Haspel. (CIA/AFP/Getty Images)

Haspel, in particular, has a bigger hurdle to clear, because most senators know very little about her. “I know nothing about the CIA nominee, couldn’t pick her out of a lineup, okay?” Sen. Bob Corker (R-Tenn.) said Tuesday. “Never met her. I have no input there.”

This is a potential new development in the Trump-Senate relationship. A few nominees were withdrawn because of scandal, but none have actually reached the full Senate for a vote and lost. Education Secretary Betsy DeVos came close, needing Vice President Pence to cast a tiebreaking vote after two Republicans defected and left the roll call at 50 to 50.

Recently, Republicans and White House officials have focused their ire on Democrats and the delay tactics they used to stall the confirmation process, even on nominees who eventually received more than 80 votes. Democrats have often forced McConnell to burn up every hour allowed for debate, stretching debate on some sub-Cabinet posts across several days and leaving little time to do much else.

This has created essentially a two-tier system of nominees, according to a senior GOP senator familiar with the views of leadership and White House officials. Trump’s advisers select those nominees who are deemed the most important, and McConnell devotes the cumbersome time to get them confirmed — letting others languish in confirmation purgatory.

But with this next round of high-level confirmations, it’s not just Democrats who are the problem. Wavering Republicans who might leave them short of a majority from within the GOP give Democrats the power to torpedo the nominee.

Take the Haspel nomination. Democrats have raised questions about her role in CIA interrogation techniques used on suspected terrorists last decade. Paul, an ideological libertarian on national security, opposes her based on her connections to interrogation practices that he likened to torture.

And if McCain were to return to the Senate by the time of her confirmation, he is not a sure yes vote. The former prisoner of war in Vietnam issued a statement expressing concern about her interrogation role.

If all 49 senators who caucus with the Democrats vote in a bloc against Haspel, without Paul and McCain she would be short of the 50 votes needed for confirmation. Democrats have voted for plenty of Trump’s Cabinet-level picks — but they have yet to provide the margin of victory with fewer than 50 Republicans backing a selection.

Some Republicans worry that the entire nomination process, beyond just these two Cabinet-level posts, would get even more partisan if Trump’s continued public attacks on special counsel Robert S. Mueller III’s investigation into the 2016 presidential election escalated to an effort to force the Justice Department to fire Mueller.

Republicans sent veiled warnings to Trump to steer clear of meddling with the investigation and to allow Deputy Attorney General Rod J. Rosenstein to continue overseeing it.

“The deputy attorney general has already said, in response to a question from me at a public hearing, that he would not carry out what he viewed to be an unlawful order,” said Sen. Susan Collins (R-Maine).

Even if there is no Mueller fallout, Haspel faces a narrow path to confirmation.

Democrats want to know precisely what her role was in the destruction of nearly 100 videotapes of the interrogations of a captured al-Qaeda leader in 2002. If the answers are not to their liking, it could spell her doom.

“What role did the prospective CIA director play in the destruction of evidence and what role did she play in enhanced interrogation?” asked Sen. Richard J. Durbin (D-Ill.). “That’s a critical question.”

Republicans have a certain amount of leverage if they want to use it to extract some concession from the administration on other issues in exchange for supporting Haspel.

Pompeo probably has an easier road to confirmation, having spent six years as a member of the House, some with Flake and a few other senators who first served there. He received 66 votes, including 15 from members of the Democratic caucus, in his January 2017 CIA confirmation.

“My sense is there’s Democratic support,” said Corker, chairman of the Senate Foreign Relations Committee.

Of the 10 Democrats now on that committee, just two voted to confirm Pompeo as CIA director. There is a chance that the committee could give a negative recommendation to Pompeo, in an 11 to 10 vote, after the confirmation hearing later this spring, but it would still probably advance to the full Senate.

Mike Pompeo meets with Sen. Bob Corker (R-Tenn.) on Capitol Hill on Monday. (Joshua Roberts/Bloomberg News)

Corker remains optimistic. “My first meeting, I will say, could not have gone any better,” he said of Pompeo.

Still, McConnell may need to do something he has yet to do in any confirmation fight in the Trump presidency: plead for Democratic votes because of insufficient GOP support.

Durbin is not sure how his more moderate Democratic colleagues will react. They would have the power to put Pompeo over the top — which could be appealing for those Democrats running for reelection in states Trump won.

“I don’t know what to expect,” Durbin said.

Read more from Paul Kane’s archive, follow him on Twitter or subscribe to his updates on Facebook.