Contrary to what many people thought after June 20, special election season is not over quite yet. Come Dec. 12, Alabama will elect a senator to replace Attorney General Jeff Sessions, who vacated the junior seat in the upper chamber of Congress.

This contest is a not a question of whether the Democrats will pull off an incredible upset, as many politicos had predicted them doing in other congressional special elections in Georgia and Montana. Alabama, long a deep red state, is still solidly Republican territory. The Democrat in the current race, Doug Jones, is essentially irrelevant.

It would even be fair to say that Alabama’s next senator will be decided on Tuesday rather than two and a half months from now. Tomorrow, Alabama Republicans will chose their candidate for the seat in a runoff, between either Luther Strange, who currently occupies the seat as an interim senator, and Roy Moore, the former Chief Justice of Alabama’s Supreme Court.

Even though the real race is between two Republicans, the result will still have a major impact on Congress and the balance of the Senate caucus. The contest has come down to a question of “establishment vs. outsider.”

Strange could be considered the very embodiment of the former. He has held the Senate seat for only seven months, but already seems to have gotten himself on Majority Leader Mitch McConnell’s (R-KY) good side. McConnell has endorsed Strange, and PACs aligned with establishment Republicans have poured millions into the race. Arguably more importantly, Strange has the endorsement of President Trump, who has a 28 point net approval rating in the state, according to FiveThirtyEight.

Moore, however, is currently leading in the polls, almost certainly because of his history of strong support for conservative social policy. Among Moore’s most infamous moments include his removal from the judicial bench when he refused to get rid of a monument of the Ten Commandments he had installed at the Supreme Court of Alabama, and when he called for the impeachment of judges who support LGBTQ rights.

After winning the open primary for the seat back in August, Moore has widened his lead further heading into the runoff against Strange, with a poll by Decision Desk HQ showing a majority of voters supporting him.

As Strange and Moore go head to head, much more than just policy is at stake. Many are viewing this contest as crucial to the future of Republicans and their ability to pass legislation.

Strange votes almost in lockstep with McConnell, with their records only diverging over a fiscal appropriations bill, according to FiveThirtyEight. Moore, however, is an unknown quantity. Should he win, the Republican caucus will be forced to deal with yet another faction in their party, this one representing the disruptive, non-establishment wing of conservatism that McConnell has had to spar with in the past.

In effect, this makes the Republican majority in the Senate more theoretical than anything else. Appeasing all sides of the party is already near impossible for McConnell to do; the Republican attempts to reform health care show this. Adding an unpredictable, reactionary senator to the mix would be catastrophic for Republicans, especially if Moore makes voting with the party an exception and not a rule.

Thus, Alabama has become excruciatingly important to not just the Republican caucus, but to the future of the country in general. Not only will a Moore win have major legislative implications, but it will show that even Trump’s own base is willing to buck him for someone they deem more reactionary.

Knowing Trump, however, he won’t care all that much. Why rip into politics when he could complain about the NFL some more?

Follow Thomas Denome on Twitter at @thomas_denome