On Wednesday, dozens of congressional Republicans will launch a final challenge to the electoral college results of the 2020 presidential election.

Congress will meet Wednesday to count and confirm each state’s electoral votes. It has become routine after recent elections for House lawmakers on the losing side to put up a symbolic fight over the results, which they can do under an 1880s law governing the process.

It has been less common for senators to join them, but this time a dozen will. Republican Sens. Josh Hawley (Mo.) and Ted Cruz (Tex.) will lead the challenge of the votes and call for an emergency audit to investigate alleged widespread fraud in the presidential election, for which there is no evidence.

It’s also unprecedented to see as many challenges to states’ results as we expect to see Wednesday. This will happen despite no evidence of widespread election fraud and as the outgoing president has refused to concede and tried to strong-arm the process at every step to stay in power.

The challenges are poised only to delay the inevitable, which is Congress confirming Joe Biden’s win. But it will force lawmakers to vote on the challenges and put Vice President Pence in the awkward position of eventually having to officially announce Biden’s win, even as he is getting pressure from President Trump to do something potentially illegal and somehow declare Trump the winner.

Here’s how we expect the day to go:

What Congress is doing on Wednesday

Throughout November and December, states certified their results. Then the electoral college voted Dec. 14 based on those results and made Biden the winner. States sent their electoral college vote totals to the new Congress to be counted and confirmed. This counting will happen on Wednesday. It’s largely a formality, since election law says Congress has to treat states’ results completed by the safe harbor deadline of Dec. 8 as “conclusive.”

Wednesday is the penultimate step in the post-election process. All that’s left after that is to inaugurate Biden.

How Congress counts the votes

Congress will meet in a joint session around 1 p.m. Eastern time, meaning both the House and Senate are together. Pence will preside over the process. He could delegate the job to another senator, but we don’t expect that.

They will go through the states alphabetically. For each state, clerks sitting below Pence will hand him the envelopes, tell him the votes, and he is supposed to read them out loud. Then they move on to the next state.

There will be precautions for coronavirus. House Speaker Nancy Pelosi (D-Calif.) told lawmakers to stay in their offices during debate. The plan is for lawmakers to stream in to vote in small groups. And masks are required on the House floor.

How challenges to state’s electors will work

For a challenge to proceed, at least one lawmaker from each chamber must object to a state’s electors. More than two dozen House Republicans have said they will try to challenge results, and a dozen GOP senators will join them — even though Senate Majority Leader Mitch McConnell (R-Ky.) has urged senators to stay away from this.

Lawmakers don’t have to give a detailed explanation of why they object; they just object in writing, which Pence will read out loud.

If there’s an objection to a state’s electors raised by both a House and Senate lawmaker, the chambers have to split up and vote on that objection. Most of this will be done silently, save for Pence reading out loud the objections.

They have up to two hours to debate each one. That means there will be simultaneous debates in the House and Senate. We expect congressional leaders in both chambers to move to put down the challenges as quickly as possible. In the House, Pelosi will let lawmakers from the states being challenged do the speaking on the Democratic side.

How we expect voting on challenges to happen

Let’s say a Republican House member and a Republican senator challenge the electoral count in Arizona. (Cruz plus as many as 10 other senators and Rep. Andy Biggs (R-Ariz.) have said they plan to object to Arizona, with other pairs of Senate and House lawmakers lined up to object to other swing states Trump lost.)

When that challenge to Arizona happens, the Senate splits off and debates this challenge for up to two hours; then each senator gets a vote on which electors to approve. The House does the same.

The Democratic-controlled House has the votes to knock down all challenges.

Senate Republican leaders have not been able to keep their party unified through this process, but they expect to have the votes to confirm Biden’s win, despite as many as a dozen Republican defections. Sen. John Thune (S.D.), the No. 2 Senate Republican, said last month that any challenges are “going down like a shot dog.” With all 48 senators who caucus with the Democrats sticking together, they only need a few Republican votes to knock down each challenge, and at least 25 Republican senators have said they don’t approve of these challenges.

Some have used sharp language to criticize these challenges. Republican senators such as Mitt Romney of Utah and Ben Sasse of Nebraska have characterized their colleagues’ challenges to certified election results as dangerous. “I could never have imagined seeing these things in the greatest democracy in the world,” Romney said in a statement. “Has ambition so eclipsed principle?”

At least one Republican critic of the objections pointed to Trump’s hour-long phone call with Georgia’s secretary of state, in which the president tried to get his loss in Georgia overturned, as all the more reason for the Republican Party to stand up to Trump and vote to certify states’ legitimate results. “To every member of Congress considering objecting to the election results,” tweeted Rep. Adam Kinzinger (R-Ill.), “you cannot — in light of this — do so with a clean conscience.”

Republican leaders’ resistance to challenging the election now is notable given that the vast majority of Republican lawmakers waited more than a month to acknowledge that Biden was the winner. Many still haven’t. But there doesn’t seem to be an appetite among a majority of Republican lawmakers to use Congress to try to overturn the will of the voters.

There’s also no legal basis for senators to question the electoral college results, since all the states that are in Trump’s crosshairs met every legal requirement for having their electoral votes recognized by Congress.

What happens if one chamber votes to accept a challenge to a state’s electors

Now we are almost certainly getting out of the realm of possibility, given the numbers. But if the Senate decided to vote in favor of a challenge to a state’s electors, there are still many hurdles to overturning Biden’s win.

The law requires both chambers of Congress to affirmatively vote to object to a state’s electors, which won’t happen with a Democratic-controlled House.

Even if both chambers somehow agreed to accept the challenge, the tiebreaker would go to the governor of the state. And all governors in contested states have certified results that Biden won.

So even if we drift far into hypotheticals on this, there are numerous checks that would protect Biden’s win.

Why this could stretch well into the night anyway

Trump lost about six swing states, and they’re spread out throughout the alphabet — Arizona to Wisconsin. Republicans who question the election results have indicated they will try to challenge all of them. Each time there’s a challenge supported by at least one member of each chamber, Congress has to split off and vote on it. Then they come back together and keep counting states. Voting will also take longer than normal because of coronavirus precautions to space lawmakers apart from each other.

What is a normally quick and easy process could get dragged into the wee hours.

Pence’s role in all this

Pence’s part here is administrative. He has no real authority to refuse to accept electoral results.

After being tight-lipped about his role in the process, he confirmed his ministerial role at the start of the joint session on Wednesday in a statement, saying: “It is my considered judgment that my oath to support and defend the Constitution constrains me from claiming unilateral authority to determine which electoral votes should be counted and which should not.”

That statement came despite — or perhaps because of — increasing pressure from Trump.

“I hope Mike Pence comes through for us,” Trump said at a rally in Georgia on Monday. “He’s a great guy. Of course, if he doesn’t come through, I won’t like him quite as much.”

“I hope Mike is going to do the right thing,” Trump told a crowd of supporters in Washington, D.C., on Wednesday.

In tweets, Trump has inaccurately claimed Pence has the authority to choose or not choose electors. (That’s Congress’s job, as we explained above.)

Last week, Rep. Louis Gohmert (R-Tex.) actually sued Pence in federal court to get rid of the Electoral Count Act and have Pence legally able to choose whatever sets of electors he wants. A Trump-appointed federal judge in Texas threw it out immediately, at Pence’s legal team’s request.

But Pence has tried to stay in the relative good graces of the president through this. Over the weekend, his office welcomed challenges to legitimate election results, saying the vice president “welcomes the efforts of members of the House and Senate to use the authority they have under the law to raise objections and bring forward evidence.”

What’s happened in past challenges to electoral results

Members of the party that lost the presidential election have raised objections after nearly every election since 2000. All have failed, and only one succeeded in splitting the chambers to force them to debate one challenge.

When certifying the contentious 2000 election, House Democrats tried to challenge Vice President Al Gore’s loss using Florida’s electoral votes, but they couldn’t find a Senate partner to get things started.

In 2005, House Democrats challenged President George W. Bush’s reelection the same way over the result in Ohio. Then-Sen. Barbara Boxer (D-Calif.) joined them, but the effort was quashed pretty quickly, including by her fellow Democrats in the Senate. House Democrats tried again in 2016 to challenge Trump’s win, but no senator was willing to stand with them.

For that challenge, it was then-Vice President Joe Biden who was presiding over everything. “It is over,” he told Democrats.

How to watch all this

The Washington Post will air the Jan. 6 proceedings in full.

This has been updated with the latest.

Correction: Congress does not vote after the vice president reads each state’s electoral college results. They only vote if there is an objection by a House and Senate lawmakers to that state.