Republicans looking to block Roy Moore from becoming a senator are exploring a number of options, though the window is closing with the Alabama Senate race just four weeks away.

After The Washington Post reported that four women described sexual advances from Moore, when they were teenagers and he was in his 30s, GOP leaders called on the candidate to quit if the allegations were true. Another accuser came forward Monday to say Moore sexually assaulted her. 

On Monday, Senate Majority Leader Mitch McConnell said he believed Moore’s accusers and urged him to step aside as the nominee. Colorado Republican Cory Gardner, chairman of the National Republican Senatorial Committee, said the Senate should expel Moore if he’s elected.

GOP lawyers scrambled last week to determine if Moore could be removed from the ballot. But the deadline for altering the ballot has passed. One potential scenario being tossed around was that Alabama Gov. Kay Ivey could move the date of the special election, reopening the window to alter the ballot. But Ivey spokesman Josh Pendergrass told The Associated Press over the weekend the governor was not considering moving the election. Pendergrass said Monday that her position had not changed.

Moore has said he will continue his campaign, calling the allegations regarding sexual misconduct untrue. But there are three potential scenarios for Republicans hoping to block Moore from coming to the Senate:

1. State party withdraws nomination 

It is still possible for the Alabama Republican Party to disqualify Moore as their nominee. In that scenario, the state party would submit a formal letter to Alabama Secretary of State John Merrill. The state party has so far remained silent on the allegations, but Jonathan Gray, an Alabama Republican consultant, said last week that the party would “self-destruct” if it disqualified Moore. He pointed to a 1986 dispute in which the Alabama Democratic Party, which dominated state politics at the time, took sides in a disagreement over its gubernatorial nominee. The Republican nominee went on to win the election.

2. Write-in campaign

Even if Moore refuses to withdraw from the race, another Republican could mount a write-in campaign. GOP Sen. Luther Strange, who was appointed to the Alabama seat, has reportedly been considering a run. But Strange would likely face the same challenges that dogged him in the primary, namely concerns around his appointment.

Strange, as the state’s attorney general, was reportedly investigating then-Gov. Robert Bentley at the time of his appointment, raising questions of a quid-pro-quo agreement. Strange has dismissed those questions as political attacks. He finished second to Moore in the primary, and lost the subsequent runoff by nearly 10 points.

With the general election roughly four weeks away, it’s not clear if a potential write-in candidate would have enough resources and name recognition to mount a successful campaign. There is the added concern for Republicans that a write-in campaign would split the GOP vote, paving the way for Democrat Doug Jones to win the seat. 

3. Senate expulsion 

If Moore does win the race, senators could expel him from the chamber. Legal precedent suggests they will have to accept him as a senator if elected, with the Supreme Court ruling in a 1969 case known as Powell v. McCormack that the House can refuse to seat a lawmaker only if he or she does not meet the constitutional requirements for office. But the court noted the chamber could expel the member once he is seated.

It is theoretically possible for the Senate to forgo regular order and expedite the vote to expel Moore, said Robert Walker, former chief counsel and staff director for the House and Senate Ethics committees. But Walker said the Senate would likely go through regular order, meaning the Ethics Committee would conduct its own investigation into the allegations.

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Walker, a lawyer at Wiley Rein, said the Ethics Committee could decide it has jurisdiction to investigate the allegations even though they occurred long before Moore was a Senate candidate.

“The Ethics Committee has come up on this issue before. And they have left the question open,” Walker said.

He pointed to a May 2008 decision by the committee not to pursue allegations that David Vitter, a Louisiana Republican, had solicited prostitutes before he was elected to the Senate. In the letter, the committee said it “should not” pursue the Vitter case, suggesting it could. The committee also reserved the right to reopen the investigation.

Walker estimated the investigation could take weeks or months. Following an investigation and a hearing, senators could opt to vote to expel Moore, which would require two-thirds of the Senate.

Only 15 members have been expelled in the history of the Senate. Fourteen of those were expelled for disloyalty during the Civil War.