The Senate Ethics Committee will immediately launch an investigation into allegations of sexual misconduct against retired judge Roy Moore if the Republican Senate candidate wins a special election in Alabama next week.

The committee doesn't require a referral from Senate leadership or another entity to initiate an investigation, just the votes of four of six committee members. With the panel split equally among Democrats and Republicans, that outcome is all but assured. Moore, projected in most public opinion polls to narrowly defeat Democratic attorney Doug Jones, would likely be called to testify under oath.

The probe, likely to be rigorous, would be carried out behind closed doors by the Senate Ethics Committee's professional, nonpartisan staff. It could take months, and might come up empty or conclude with an "admonishment" — essentially a slap on the wrist. The committee could also recommend that the full Senate vote on a motion to "censure" Moore or expel him from Congress.

“If he were to be elected, he would immediately have an issue with the Ethics Committee that they would take up,” Senate Majority Leader Mitch McConnell, R-Ky., told reporters Tuesday during a Capitol Hill news conference.

Read more: Court records suggest Roy Moore dated his wife while she was still married

Moore, 70, has been accused by multiple women of sexual misconduct decades ago when they were teenagers and he was in his 30s. Among them, one woman claims she was 14 at the time, two years under the age of consent; another woman said she was of legal age but alleges Moore assaulted her.

Moore, twice removed as chief justice of the Alabama Supreme Court for ignoring rulings from the federal bench, vehemently denies all accusations.

He has climbed back into the race against Jones after seeing his support plunge when the revelations first surfaced. President Trump has endorsed Moore, outside groups loyal to the White House have invested on his behalf, and the Republican National Committee has re-engaged with money and manpower.

“Not a shred of credible evidence has been offered up against Roy Moore for any allegation,” Moore campaign manager Brett Doster said in an email exchange with the Washington Examiner. “We will win next Tuesday, and we don’t expect an ethics investigation because no wrong has been committed.”

But most Senate Republicans haven’t changed their opinion; they don’t think Moore is fit to serve. Sen. Cory Gardner of Colorado has made clear that the National Republican Senatorial Campaign Committee, the party’s Senate campaign arm that he chairs, will not reengage. That decision isn’t made without McConnell’s blessing.

So, a Senate Ethics Committee investigation into Moore remains a near certainty, even though the panel doesn't usually examine matters that occur before an individual becomes a senator, given the political risk of sweeping allegations of sexual misconduct under the rug in the wake of the downfall of Hollywood mogul Harvey Weinstein.

Senate Republicans said the probe would be aggressive but fair, taking into account the rights of the accusers as well as the accused. If the Senate votes on expulsion, a two-thirds vote, 67 senators, would be required to kick Moore out of Congress.

"There’s due process. It’s not just hang 'em and then give 'em a fair trial. There will have to be a process by which they gather information and then they make a decision, and that requires a majority vote," said Senate Majority Whip John Cornyn, R-Texas, who previously served on the ethics panel. "They need to make some fundamental decision like, are they going to consider pre-Senate conduct, which, that would represent a change in the policy, because the last time I was on the ethics committee, they only considered conduct while you were in the Senate."

The Senate Select Committee on Ethics is led by chairman, Sen. Johnny Isakson, R-Ga., and vice chairman, Sen. Chris Coons, D-Del. Often, the committee chooses not to publicize the existence of an investigation to protect a senator's reputation if the probe finds no malfeasance. Given the public scrutiny, Senate Ethics would probably acknowledge an investigation into Moore, as the panel did when it resumed the probe into Sen. Bob Menendez that it halted while the New Jersey Democrat stood trial for corruption.

Senate Republicans can’t block Moore from being seated. He might assume the same committee assignments as appointed Sen. Luther Strange, R-Ala., the member he would replace, joining the Agriculture, Armed Services, Budget, and Energy panels (not Judiciary, the committee Moore has expressed an interest in because it processes the nomination of federal judges.)

Based on comments McConnell made on Sunday — that the outcome of the Alabama race is in the hands of the voters — some political observers concluded that Senate Republicans were backing off threats to investigate and possible expel Moore. Those assumptions were incorrect, McConnell said.

The leader told reporters that he was simply stating the obvious. His effort to replace Moore as the Republican nominee on the Dec. 12 ballot failed, so voters would indeed have the final say. However, a Senate Ethics Committee probe, the procedural precursor to any floor vote to expel a senator, still awaits the retired judge.

“There’s been no change of heart. I had hoped earlier he would withdraw as a candidate. That’s obviously not going to happen,” he said.