US President Donald Trump has recorded an audio message for a Republican Senate candidate accused of sexual misconduct, on the eve of the election.
The president has thrown his political weight fully behind former Alabama judge Roy Moore, who is vying with Democrat Doug Jones for the seat.
Mr Moore denies claims by several women that he made unwelcome sexual advances, mostly when they were teenagers.
The race remains too close to call a day before Alabamians go to the polls.
Tuesday’s election could alter the balance of power in the Senate ahead of next year’s mid-term Congressional elections.
Mr Trump has pointed to Mr Moore’s repeated denial of the allegations against him as part of his reason for endorsing the former Alabama supreme court judge.
One woman alleges Mr Moore molested her when she was 14. Another says he tried to rape her.
At a rally on Monday night, Mr Moore reiterated his denials, again questioning why his accusers kept quiet for 40 years while he held various political offices.
Speaking alongside Mr Trump’s former chief strategist, Steve Bannon, in front of a crowd which chanted the president’s slogan “Drain the Swamp”, Mr Moore drew heavily from the Bible.
“I want to make America great again with President Trump,” he said. “I want America great, but I want America good, and she can’t be good until we go back to God.”
Mr Moore’s campaign rolled out an audio message earlier on Monday with a recording of Mr Trump telling voters his agenda will be “stopped cold” if Mr Moore were to lose.
At a rally in Florida on Friday, Mr Trump proclaimed his support for the 70-year-old conservative Christian.
Fitting end to unpredictable year
Analysis by Anthony Zurcher, BBC News
Democrat Doug Jones is ahead by 10 points. No, Republican Roy Moore has a nine-point lead.
The latest batch of Alabama opinion polls are having a difficult time contending with the idiosyncrasies of a low-turnout, mid-December special election, a scandal-plagued Republican candidate in a deeply conservative state and a Democratic base that, while small, may be intensely motivated.
With so many variables at play, it will be tough to draw conclusions about the results of this election – but that won’t deter anyone.
A Jones win would not only be seen as a stern rebuke of President Trump, who has put his name on the line for Moore, it would make Democratic control of the US Senate in 2019 a much more realistic possibility.
If Mr Moore prevails, it’d be a prize for the anti-establishment Steve Bannon faction of the Republican Party and an indication that, when it comes to a seat in the US Senate, ideology matters most for some.
Back when Mr Trump named Senator Jeff Sessions to be attorney general last November, no one imagined all eyes would now be on Alabama. It makes for a fitting end to an entirely unpredictable year, however.
Many other national Republicans, including Senate Majority Leader Mitch McConnell, have distanced themselves from their party’s candidate.
But Richard Shelby, Alabama’s other senator, said on Sunday he could not endorse Mr Moore because he found his accusers “believable” and the state “deserves better”.
The Moore team is banking on voters in the Deep South staunchly conservative heartland refusing to pick a Democrat.
On Monday in Birmingham, Mr Jones, a 63-year-old prosecutor, accused his Republican opponent of hiding.
In Washington, a Democratic lawmaker has sent a letter to the Senate’s Sergeant at Arms urging that Congress take steps to ensure the safety of teenagers working in the Senate page programme from Mr Moore’s “predatory conduct”.
“I believe my fears are well founded”, wrote Wisconsin Congresswoman Gwen Moore, citing the multiple allegations against Mr Moore.
Mr Moore has kept a low profile in recent days, but he said in an interview with The Voice of Alabama Politics on Sunday that he “never molested anyone” and had been a victim of “ritual defamation”.
Mr Jones has spent the past week rallying African-Americans, and he held a series of rallies across the state on Sunday.
Former President Barack Obama and former Vice-President Joe Biden have recorded robo-calls for him.
Former Secretary of State Condoleeza Rice, an African-American Alabamian, released a statement on Monday urging voters “to reject bigotry, sexism, and intolerance”, but did not include an endorsement for either major party candidate.
“It is imperative for Americans to remain focused on our priorities and not give way to side shows and antics,” she said, adding that the state needs “an independent voice in Washington”.
Tuesday’s winner will take the seat held previously by Trump administration Attorney General Jeff Sessions.
Mr Trump won the state by 28 percentage points over over Hillary Clinton in last year’s.