BIRMINGHAM, Ala. -- U.S. President Donald Trump said electing a Democrat as Alabama's next senator "would be a disaster," as the president tried to steer the Alabama race toward partisan legislative concerns and away from allegations of sexual misconduct against Republican Roy Moore.

While Republican Senate leaders have criticized their party's nominee, Trump plunged into the Alabama Senate race with a pair of tweets Sunday bashing Democrat Doug Jones.

"" he wrote from Florida, referring to Democrats' congressional leaders Chuck Schumer and Nancy Pelosi.

For weeks, accusations that Moore, now 70, sexually molested or assaulted two teens, ages 14 and 16 -- and tried to date several others -- while he was in his 30s have taken centre stage in the heated Alabama race. Moore denied the allegations of misconduct and said he never dated "underage" women.

Trump's words could be a boost to the Moore camp, since Democrats' hopes in the race partly depend upon peeling away Republican support from Moore in the deeply red state.

Moore's campaign quickly touted Trump's comments on social media and in a fundraising email to supporters that lashed out at Republican leaders as much as it did Jones.

"President Trump calls them like he sees them. And, he's got my opponents in D.C. scrambling," Moore wrote in a fundraising email.

The Republican candidate has made limited public appearances since the allegations surfaced earlier this month.

Jones, speaking to reporters in Birmingham, shrugged off Trump's criticisms, saying he would not be a partisan voter. He said Alabamians are focused on issues such as the economy, education and health care.

"My record speaks for itself ... I think I am very strong on the issues that the people of Alabama care for," Jones said.

Jones, a former federal prosecutor, said he would be an independent voice in the U.S. Senate, similarly to his political mentor, the late U.S. Sen. Howell Heflin, who represented the state for nearly 20 years.

Jones' campaign issued a more biting statement saying, "Roy Moore was unfit for office even before nine Alabama women served as witnesses to all Alabamians of his disturbing conduct."

Trump's comment in the race signalled that the success of his legislative agenda outweighs widespread concerns from national Republicans, many of whom are repulsed at the prospect of seating Moore.

Top Republicans in Congress, including Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan, have called for Moore to leave the race, and the Republican National Committee and the National Republican Senatorial Committee have pulled their support for his campaign.

GOP Sen. Tim Scott of South Carolina said the Dec. 12 election has become a referendum on "the character of the country" that transcends partisan politics.

"In my opinion, and in the opinion of many Republicans and conservatives in the Senate, it is time for us to turn the page because it is not about partisan politics. It's not about electing Republicans versus Democrats," Scott said Sunday on ABC's "This Week."

Republican Sen. Lindsey Graham of South Carolina, who has also called for Moore to step down, said Sunday on CNN's "State of the Union" that Trump is "definitely trying to throw a lifeline to Roy Moore."

But when it comes to Moore, Graham said it's unclear "what winning looks like."

"If he wins, we get the baggage of him winning and it becomes a story every day about whether or not you believe the women or Roy Moore, should he stay in the Senate, should he be expelled. If you lose, you give the Senate seat to a Democrat at a time we need all the votes we can get," he said, referring to Republicans' current 52-48 majority in the Senate.

"The moral of the story is: Don't nominate somebody like Roy Moore who could actually lose a seat that any other Republican could win," Graham said.

Sen. John Thune of South Dakota, the No. 3 Republican in the Senate, said he'd like to see Trump "come out and support what many of us have said and that is that Roy Moore needs to step aside" and "allow somebody else to be a write-in candidate."

He said on "Fox News Sunday" that if Moore ends up winning and comes to Washington in January, he will be the immediate subject of an ethics investigation, "which is going to be a cloud that he'll be operating in and it's going to be a distraction for us and for our agenda."

Trump has no campaign events for Moore scheduled at this time, said White House spokeswoman Lindsay Walters.

Trump backed incumbent Sen. Luther Strange in the Alabama Republican primary but moved quickly to embrace Moore after he won. The seat opened up after Republican Jeff Sessions was tapped as U.S. attorney general.