There's no doubt about the outcome — Congress will ratify Joe Biden's election win and he'll be sworn in on Jan. 20 — but that won't stop today's political theater that may drag late into the night.

• Here's our guide to watching the certification debate, with input from legislative aides, historians, election experts and Axios' Ursula Perano.

Details: The House of Representatives and Senate will meet in joint session in the House chamber at 1 p.m. ET to officially count and certify the 538 electoral votes ratified in all 50 states and the District of Columbia.

• Expect objections (in alphabetical order) from members in both chambers to results from Arizona, Georgia and Pennsylvania. There may be other objections raised, but to be debated they must be raised in both chambers.
• Republican Sens. Ted Cruz of Texas, Kelly Loeffler of Georgia and Josh Hawley of Missouri will be among the objectors to watch.
• Nothing's stopping President Trump from live-tweeting the proceedings — and he has summoned his supporters to the nation's capital for protests.

Why it matters: The debate won't change the election results. There are more than enough Republican senators and members of the House who have indicated they will recognize the certified votes from the states to ensure a majority vote to reject the objections.

• But it will shake many Americans' confidence in their democracy and delegitimize Biden's legitimacy in the eyes of voters aligned with Trump. It will also draw battle lines for the 2024 GOP presidential primary.
• It also could test the potential for future alliances between Biden and embattled Senate Majority Leader Mitch McConnell, per Axios' Margaret Talev — if McConnell determines Democrats can help him manage this breakaway flank of his own party.

How it works: Vice President Mike Pence will serve as presiding officer. If he decides to delegate the job, which is not expected, it would fall to Sen. Chuck Grassley as the Senate President Pro Tempore.

Trump has been pressuring Pence to overturn the election results, but that is not within Pence's ceremonial powers.

• Pages will bring in ceremonial mahogany boxes full of the votes from the states, which are placed at the front of the chamber. Pence will then present the certificates of the electoral votes in alphabetical order.
• He'll hand each envelope to one of four tellers — who will be the ranking and minority members on the Senate Rules and House Administration Committees. They'll open the envelopes and read the vote totals.
• Pence will start with Alabama and end with Wyoming, stating that the certificate from each state “seems to be regular in form and authentic.”
• He has the power to recognize any lawmaker who objects.
• Any member may rise and object. If it is in writing and signed by both a member of the House and a member of the Senate, then the Senate leaves the House chamber and marches back across to the Senate chamber for debate.
• Each chamber separately debates each objection, with a two-hour limit, and holds a vote on the challenge. Then the Senate rejoins the House and the results of the votes are announced.
• Following the vote, they will move on to the next state and begin the process again.
• Once all votes have been recorded and counted, Pence will announce whether Biden and Vice President-elect Kamala Harris have received the required majority votes. If so, the announcement will be deemed "a sufficient declaration."

Timing: The process is expected to continue late into Wednesday evening, and could spill into Thursday depending on how long lawmakers want to draw out the objection process.

Go deeper: Read the Congressional Research Service guide to counting the votes