Updated at 1:45 p.m. ET

It may come and go without much fanfare, but on Tuesday, the U.S. will pass a key deadline cementing President-elect Joe Biden's victory as the 46th president.

The day, Dec. 8, is known as the "safe harbor" deadline for states to certify their results, compelling Congress to accept those results.

Most Americans see Election Day as the end of the long political season aimed at choosing new federal leadership, but it's really only the beginning.

On Nov. 3, voters actually voted for which Electoral College electors to represent them, not for the presidential candidates themselves. Those electors then meet and cast votes, which are counted and finalized by Congress.

"The Electoral College is pretty complicated because it's a process," said Rob Alexander, a political science professor at Ohio Northern University and the author of a book on the Electoral College. "It's not one thing, it's not one event."

Court losses have continued to pile up for President Trump, and experts have already written off his ongoing crusade against the presidential election results as a disinformation campaign. But it shows no sign of stopping.

Trump's campaign team released a statement Tuesday attempting to downplay the deadline.

"Despite the media trying desperately to proclaim that the fight is over, we will continue to champion election integrity until legal vote is counted fairly and accurately," said attorneys Rudy Giuliani and Jenna Ellis.

But experts say Tuesday's deadline further limits what Trump's allies in Congress can do in terms of contesting the results.

"The best way to think of it is... as another nail in the coffin," tweeted Rick Hasen, an election law expert at the University of California, Irvine.

The process is continuing, and what has been clear for a month is still clear: Joe Biden will be the next president.

Poorly written legislation

The Tuesday deadline was put in place by a piece of 130-year-old legislation widely criticized as "almost unintelligible."

The Electoral Count Act of 1887 came as a reaction to the presidential election of 1876, which saw Democrat Samuel Tilden win the popular vote but ultimately lose the presidency to Republican Rutherford B. Hayes because of contested election results coming from three Southern states under the control of Reconstruction governments.

Congress had no rules in place to deal with such a scenario, so it created an ad hoc commission to decide the presidency and then passed the 1887 law afterward to avoid similar situations in the future.

The legislation is "extraordinarily complex" and "far from the model of statutory drafting," according to an analysis by the National Task Force on Election Crises, but it does create a clearer timeline for when states need to have their election results finalized.

Electoral College electors are scheduled to meet in states across the country on the first Monday after the second Wednesday in December (Dec. 14 this year) to cast their votes.

And if a state has finalized its results six days before then, according to the ECA, then those results qualify for "safe harbor" status — meaning Congress must treat them as the "conclusive" results, even if, for example, a state's legislature sends in a competing set of results.

Every state except Wisconsin appears to have met the deadline, according to The Associated Press. Wisconsin's 10 electoral votes are still expected to be cast for Biden on Monday; he won the state by just over 20,000 votes.

"If a state can conclude its process of appointing electors by that [safe harbor deadline] then Congress is bound by federal law to accept the slate of electors that is arrived upon by that date," said Rebecca Green, the co-director of the Election Law program at William and Mary.

Both Green and Alexander, of Ohio Northern, said they expect a few "faithless electors" to vote on Dec. 14 for a different candidate than voters chose but nowhere near enough to affect the underlying result.

A majority of states have some sort of law that either removes, penalizes, or cancels the votes of such errant electors, and the Supreme Court upheld the constitutionality of such rules earlier this year.

Trump allies in Congress may still look to stir drama during the electoral vote counting on Jan. 6, but a Biden presidency at this point is virtually certain.

Despite Trump's insistence that there was a widespread cheating scheme and therefore the results need to be overturned, no evidence to support that theory has come to light, Green noted.

"We saw in the instance of the courts that the answer was 'no,' barring credible evidence," Green said. "And I have no reason to believe that the institution of Congress will not follow that similar path."

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