Alabama's write-in Republican Senate candidate brushed off President Trump's Monday endorsement of Roy Moore, saying he sensed reluctance from Trump.

"The president appears as frustrated as most Alabamians with the choices they had," former Marine Col. Lee Busby said in an email to the Washington Examiner.

Busby, a top aide to White House chief of staff John Kelly when Kelly was a Marine Corps general, said they haven't spoken in a year. Busby has no plans to seek prominent GOP endorsements.

Many Alabama Republicans, including Sen. Richard Shelby, aren't backing Moore amid allegations he sexually and romantically pursued teens as young at 14 when he was in his 30s.

Trump endorsed Moore in a tweet, writing "we need Republican Roy Moore to win" so that he can support various causes in the Senate.

Busby announced a write-in campaign last week after Moore refused to step down. Polls show a close race between Moore and Democrat Doug Jones, a former U.S. attorney.

"If you look at my positions and views, it's evident I am the best choice for the Trump agenda," Busby told the Examiner. "Alabamians will decide this for themselves. The polls are starting to show that people wanted another choice, I am that choice."

Alabama has a high burden for ballot access, so minor parties don't appear on the ballot. Libertarian Ron Bishop, however, is also courting disaffected Alabamians.

Bishop predicted a showing in the high single digits on the day Moore was first accused of sexual misconduct, but told the Examiner in an email last week that he could imagine an even larger vote share.

"We are very optimistic that we will have a strong showing in the polls (if not win it) if people will take the time to get out and vote for policy over party," Bishop said. "The most comments we get are from people that were not going to vote December 12th, but see there is a financially conservative candidate out there they can back. They may not agree with our platform completely, but they see us as a better alternative."

Write-in candidates rarely win elections to statewide offices. A notable exception is Alaska Sen. Lisa Murkowski's 2010 win as a write-in candidate after losing the Republican primary.

Busby said he remains optimistic after Trump threw his support behind Moore, who the president campaigned against ahead of a September Republican primary, warning he was less electable than appointed Sen. Luther Strange.

"Seven days after a cold start, we are building momentum," Busby said.