House Democrats are just starting to come to terms with the consequences of a tiny majority in the 117th Congress, beginning on January 3, 2021.

Such a small majority could potentially pose a challenge for House Speaker Nancy Pelosi, D-Calif., to return to the Speaker’s suite.

The reason? It’s about the math. It’s about the math. It’s about the math.

The ENTIRE House elects the Speaker of the House. In fact, by rule, it’s the VERY FIRST THING the House must do after constituting a quorum of members on January 3, 2021.

So, if the House is comprised of 435 members, the House Speaker needs 218 votes. The Speaker needs an outright majority, not just a plurality of the House at that given moment.

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This is a problem for Pelosi if the House Democratic Caucus is whittled down to a figure in the low 220s. Say, 223 or 222 Democrats, after all the races are called. Pelosi, or any successful candidate for Speaker, can’t dip below 218.

Some Democrats could oppose Pelosi because of Democrats failing to add seats in this election. Others could vote nay simply because they want a change at the top. Pelosi has been the Democratic Leader or Speaker since 2003. She became Democratic Whip in 2001. Such longevity in leadership is almost unheard of.

The late House Speaker Sam Rayburn, D-Texas, was either Speaker, Majority Leader or Minority Leader in every Congress between 1937 and 1961.

Pelosi secured 220 votes for Speaker at the start of the current Congress out of 430 total votes cast.

There were defections. Some of the defections came from Democrats who lost or who appear to have lost this fall. Still, others remain on board. Here’s a look at Democrats who voted present or voted for someone besides Pelosi in 2019:

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Rep. Anthony Brindisi, D-N.Y., appears to have lost. He voted for Joe Biden.

Rep. Jim Cooper, D-Tenn., voted present.

Rep. Jason Crow, D-Co., voted for Sen. Tammy Duckworth D-Ill.

Rep. Joe Cunningham, D-S.C. lost his race. He voted for Rep. Cheri Bustos, D-Ill.

Rep. Jared Golden, D-Maine, voted for Bustos.

Rep. Ron Kind, D-Wisc., voted for the now late Rep. John Lewis, D-Ga..

The race of Rep. Conor Lamb, D-Pa., still hasn’t been called. He voted for Rep. Joe Kennedy, D-Mass.

The race of Rep. Ben McAdams, D-Utah, is still up in the air. He voted for Rep. Stephanie Murphy, D-Fla.

Rep. Kathleen Rice, D-N.Y., voted for Stacey Abrams.

Rep. Max Rose, D-N.Y., appears to have lost. He voted for Duckworth.

Rep. Kurt Schrader, D-Ore., voted for Rep. Marcia Fudge, D-Ohio.

Rep. Mikie Sherrill, D-N.J., voted for Bustos.

Rep. Elissa Slotkin, D-Mich., voted present.

Rep. Jeff Van Drew, R-N.J., was a Democrat at the time. He voted present.

Rep. Abigail Spanberger, D-Va., appears to have won her race. She also voted for Bustos

So, expect a lot of pressure on Cooper, Crow, Golden, Kind, Rice, Schrader, Sherrill and Slotkin when it comes to their vote for Speaker.

Remember, Pelosi didn’t have the votes to become Speaker immediately after Democrats captured the majority in the fall of 2018. But she wrapped everything up by January.

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“She’s the best vote counter,” said Pelosi’s former Chief of Staff Danny Weiss in an interview. “She’ll know what kind of deal to arrange in order to get the needed votes.”

And, you can’t beat someone with nobody.

“I would still put the odds on her as the favorite because of the combination of skills that she brings and because of the absence for the moment of another, singularly unifying person in the caucus,” said Weiss.

That said, there is a movement by some Democrats to draft House Democratic Caucus Chairman Hakeem Jeffries, D-NY, to become Speaker. (A spokesperson for Jeffries quickly shut down the suggestion and told Fox News the Brooklyn Democrat is running again to be chairman of the Democratic caucus.) Jeffries quietly tinkered with a bid two years ago had Pelosi stumbled. But Pelosi soon marshaled enough votes. And, it’s unclear if anyone could get within striking distance of 218 votes on the floor.

Former Rep. Heath Shuler, D-N.C., ran against Pelosi in late 2010 after Democrats lost control of the House. But Shuler didn’t come close to beating Pelosi. She vanquished the former NFL first round draft pick in the Democratic Caucus vote, 150-43.

“If you were going to challenge Nancy Pelosi, it is an uphill battle,” said Shuler in an interview. “There’s no better politician. She understands the game better than anyone.”

Rep. Tim Ryan, D-Ohio, challenged Pelosi in a leadership race in 2016 after Democrats failed to win the House.

Without question, Pelosi is the best vote counter in Congress.

Shortly before the leadership 2016 vote, myself and another reporter asked Pelosi how much support she had from her caucus as she rushed into the Democraic Cloakroom off the floor. It was hard to hear Pelosi over the din in the hallway. But I thought she said “three fourths.”

“Three-fourths?” I asked to clarify as Pelosi disappeared into the cloakroom.

Without missing a beat, Pelosi stuck her head back around the door of the cloakroom and into the hall.

“Two-thirds, Chad,” Pelosi corrected, waving her finger. “Two-thirds.”

Democrats cast their ballots for Minority Leader in a closed door meeting a few days later. Pelosi defeated Ryan.

She garnered precisely 67 percent of the vote.

Ryan is not running against Pelosi this year.

And, even if there was someone to run against Pelosi, could they command 218 votes on the floor?

Pelosi drew plaudits from Democrats for going head-to-head with President Trump over the past few years. Pelosi eventually rolled the President during the 2018-2019 government shutdown. Democrats will remember that. But, if Biden prevails, could the lack of a foil for Pelosi work against her?

Unclear.

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Former House Speaker John Boehner, R-Ohio, stepped down in 2015 after his support eroded. By the same token, there’s a reason why House Minority Leader Kevin McCarthy, R-Calif., didn’t matriculate to Speaker after Boehner stepped aside. McCarthy lacked the votes.

The House of Representatives is barred from doing anything until it elects a Speaker at the start of a new Congress.

A vote for Speaker hadn’t gone to a second ballot since 1923. House Speaker Frederick Gillett, R-Mass., finally prevailed on the ninth ballot a few days after voting began.

In 1849, the House burned an entire month trying to select a Speaker before settling on Howell Cobb, D-Ga.,. But that was nothing compared to 1856. In that instance, the House devoted two months to electing Nathaniel Banks, D-Mass., on the 133rd ballot.

And you thought the biggest challenge facing Congress was certifying the electoral college results in January?

This could get messy.

House Democrats are scheduled to hold internal leadership elections starting on November 17. It’s unclear if the House could delay those elections.

“I feel like we don’t have enough information to make a decision,” conceded one House Democrat. “We have races which aren’t even done yet.”

And therein lies the rub.

No one knows who is President yet.

No one knows how many seats Democrats will have.

No one knows how they will cast their ballots for Speaker on January 3.

There’s a lot to figure out.

But the math remains the same: 218. And it’s unclear what is the right cocktail of votes to elect the next Speaker of the House.

Fox News' Marisa Schultz contributed to this report.