On Dec. 12, Mr. Moore will face Doug Jones, a former federal prosecutor and the Democratic nominee, in a race that will test the party loyalties of center-right voters who may be uneasy about their nominee. It may also reveal just how reliably Republican the state has become in the quarter-century since a Democrat last won a Senate election here.
Mr. Jones said in an interview Tuesday afternoon that he was preparing to fight the general election around âkitchen-table issuesâ like health care, as well as questions of character. Without naming Mr. Strange or Mr. Moore, he alluded to their political baggage, arguing voters were fed up with politicians who have âtheir own personal agenda, whether thatâs a corrupt agenda, or whether thatâs just an agenda that is out of step with the people of the state.â
âPeople are tired of being embarrassed in this state,â Mr. Jones said. âPeople want to see someone who can get things done.â
But Mr. Moore, 70, has proved himself to be a political survivor since he first rose to prominence. He has been effectively removed from the State Supreme Court twice â the first time in 2003 over a statue of the Ten Commandments in the courthouse, and the second over same-sex marriage licenses.
And in recent days, both the president and Vice President Mike Pence have campaigned for Mr. Strange. Mr. Trump, an enormously popular figure in Alabama, visited the state on Friday, casting aside the tradition of presidents treading carefully in contested primaries, as well as the warnings from his own advisers that he was putting his persuasive powers on the line for a candidate trailing in the polls.
Yet instead of delivering a tightly crafted testimonial, the president rambled for nearly an hour and a half about a range of topics, while openly questioning whether he was making a mistake coming into the state for Mr. Strange, who oriented his entire campaign around Mr. Trumpâs endorsement and stood looking on with a red Make America Great Again hat atop his head.
Mr. Strangeâs defeat was the first time an incumbent senator with active White House support has lost since 2010, when the Arlen Specter, the longtime senator of Pennsylvania, was beaten in a Democratic primary after switching parties.
But his loss was not just a blow to Mr. Trump. Mr. Moore relentlessly linked the senator to Mr. McConnell, who has made a priority of protecting his caucus from intraparty challenges, but is an increasingly toxic figure among grass-roots Republicans. Despite the money and staff he directed to the race, Mr. McConnell became as much a liability as he was an asset, leaving Republicans nervously wondering what that may portend in other primaries next year.
Mr. McConnell and his allies were jolted with another reminder of their limited control on Tuesday, when Senator Bob Corker of Tennessee, a popular incumbent, announced he would not run for re-election. As the first senator to opt out of seeking another term in 2018, Mr. Corker opened the way for another rowdy Southern primary in which the national partyâs influence may be sorely tested.
Mr. Strangeâs demise, however, was in some respects as much a local phenomenon as a national one, stemming from his appointment this year by then-Gov. Robert Bentley to fill the seat vacated by Attorney General Jeff Sessions. Mr. Strange, the stateâs attorney general at the time, was overseeing an investigation into Mr. Bentleyâs personal relationship with a close aide, suggesting to many in a scandal-weary state that there may have been a corrupt bargain. The newly appointed senator denied any wrongdoing, but never fully confronted the issue in a way that would eliminate the lingering cloud over the appointment.
And by Monday, an adviser to Mr. McConnell, anticipating defeat, started to privately make the case that it was Mr. Bentleyâs scandal and the circumstances around the appointment that was most to blame for Mr. Strangeâs lackluster support.
When the Alabama race started, it was with less fanfare, merely a side effect of Mr. Trumpâs selection of Mr. Sessions as attorney general.
Republicans typically win federal races in Alabama without difficulty, so there was little immediate concern about the fate of Mr. Sessionsâs seat, and less still after the appointment of such a conventional politician as Mr. Strange.
Mr. Strangeâs status as a proxy for the Republican establishment and a test of the presidentâs sway came about almost by accident â a consequence of factors having little to do with Mr. Strange himself, most of all Mr. McConnellâs determination to crush electoral threats on the right.
Seeking to ward off insurgents like Mr. Moore and Representative Mo Brooks, who finished third in last monthâs primary, Mr. McConnell forcefully backed Mr. Strangeâs bid to have his appointment affirmed by voters.
The Senate Republican leader treated Mr. Strange as the political equal of his elected colleagues and ordered strategists in Washington not to work against him. Mr. McConnell and a host of other senators lobbied an initially reluctant Mr. Trump to get involved on Mr. Strangeâs behalf over the objections of some advisers. The confusing crosscurrents of the party were on vivid display when the president campaigned for Mr. Strange on Friday.
As staff members from the partyâs campaign arm allied with Mr. McConnell looked on, Mr. Strange told the conservative audience that they should elect him so he could âstand up toâ Mr. McConnell.
And then the president took the stage and assured attendees he would back Mr. Moore were Mr. Strange to lose, comments that were soon made into an online ad by an anti-establishment conservative group.
Predictably then, the race took on a life of its own, carrying outsize implications for the president and his perceived grip on the Republican Party.
Mr. Strange and his political allies bombarded Alabama voters with a message of total fealty to Mr. Trump, all but trying to put the president on the ballot. Mr. Trump lauded Mr. Strange as an indispensable man, at least when sticking to the staff-crafted script.
Mr. Strange made little attempt to find a new, more moderate universe of voters in the runoff who would recoil from the thought of Mr. Moore as their senator, a strategy fashioned next door in Mississippi when Senator Thad Cochran found himself in a runoff with a hard-line primary challenger in 2014. In fact, some strategists who had been with Mr. Cochranâs campaign said they did not hear from Mr. Strangeâs advisers.
At a rally for Mr. Strange in Birmingham on Monday night, Mr. Pence drew a direct equivalency between Mr. Strangeâs fate and the aspirations of the White House. Mr. Pence stressed frequently that he was speaking âon President Trumpâs behalf,â and said Mr. Trump had personally dispatched him to ask Alabama to heed his will.
Urging people to recruit their neighbors to vote, Mr. Pence invoked the presidentâs name again: âTell them President Donald Trump needs them to vote for Senator Luther Strange.â
At the same time Monday, Mr. Bannon was standing at a rally for Mr. Moore on Alabamaâs gulf coast, assuring the pro-Trump audience that a vote for the former judge equaled âa vote for Donald J. Trump.â
The perils of presidential involvement were obvious to some, and conservative allies of Mr. Trump, including Mr. Bannon, had counseled him not to meddle in Alabama. To a certain faction of advisers, the race looked like a no-win proposition for the president, since Mr. Trumpâs base overlaps so heavily with Mr. Mooreâs.
And then there is Alabamaâs famous, and at times infamous, distaste for being told what to do by Washington.
Steve Flowers, a state legislator turned columnist who has written about the stateâs sometimes tragic and always colorful history, noted in an interview that Alabamians âtend to resent outside influences a lot of the times.â
Siding with Mr. Strange, the president was warned early in the summer, would risk fracturing his own bloc. He did it anyway, giving in to the preferences of other Republican leaders, and to his own soft spot for a low-maintenance legislator with the memorable nickname âBig Luther.â
But he was not the only prominent figure here to gamble on Mr. Strange. Senator Richard Shelby, a pillar of Alabama politics for over 45 years, dispensed with his usual caution to support a longtime friend. But he saw how the political winds were blowing well before Tuesday.
On a get-out-the-vote conference call with Mr. Strangeâs supporters this month, he recounted an anecdote about the 1970 Democratic governorâs race here between Albert Brewer, a racial moderate, and the segregationist George C. Wallace, a divisive figure in his time. After it became clear that Mr. Wallace had won, the University of Alabamaâs young, progressive president, F. David Mathews, mournfully turned to his family and said they would have to âget used to living with George Wallace.â
Now, Mr. Shelby said, they may have to get used to living with Mr. Moore in the Senate, where he could be just as divisive.