No one has been expelled from the Senate since the Civil War

The news did not improve this week for Roy Moore, the Alabama Republican nominee for a U.S. Senate seat who is facing sexual assault allegations. While new accusers came forward, several of Moore's previous, prominent supporters took a step back.

Nonetheless, Moore's prospects of a Senate career remain remarkably good. And the realization is setting in on official Washington that senators may have no good options for keeping Moore out if he wins at the ballot box next month.

All efforts to recruit a suitable write-in opponent seem to have failed so far. And Alabama Gov. Kay Ivey has made it clear she would not delay the election or otherwise change the rules to block Moore.

Could the Senate block his seating?

Unlikely. Assuming Moore wins, as is still very possible given his base of support and the conservative bent of the state, the Senate would be obligated to seat him under the terms of the Constitution unless the vote itself is declared invalid.

The Supreme Court ruled in 1967 in Powell v. McCormack that a chamber of Congress cannot bar a duly elected member whom the other members regard as distasteful, even one accused of stealing public funds. The court was especially doubtful about conduct that occurred prior to the beginning of the congressional session in question. So if Moore must be seated, why not seat him and then move to expel him?

The expulsion idea, obviously a last resort, was first raised by Colorado Sen. Cory Gardner, who happens to be the chairman of the National Republican Senatorial Committee, tasked with getting Republicans elected to the Senate. Gardner's job is to help his party hold and augment its Senate majority in the 2018 midterm elections.

But whatever threat the GOP may perceive to its wider electoral fortunes, expulsion seems a long shot under any circumstances. There is no precedent for expelling a duly elected Senate member for actions committed before he took office.

There is little precedent for expelling senators at all.

Have other senators been expelled?

One senator was expelled for treason in 1797, and 14 were expelled in 1861 and 1862 for aiding the Confederacy in the Civil War.

Since then, there have been 17 efforts to expel, but the Senate has never mustered the necessary two-thirds vote to do so.

In a few cases, the offending senator has either died before the expulsion vote could be taken or retired with the end of his term. A half-dozen other senators found the proceedings sufficient cause for them to resign.

Who was the last senator to face expulsion?

The most recent of these was John Ensign, a Nevada Republican, who resigned in 2011 over accusations of financial improprieties stemming from an extramarital affair.

In 1995, Oregon Republican Bob Packwood resigned in response to a Senate Ethics Committee vote recommending his expulsion after numerous women's accounts of sexual harassment.

In 1982, New Jersey Democrat Harrison Williams resigned after being convicted of bribery and conspiracy in the ABSCAM corruption sting run by the FBI.

Are there other things the Senate has tried to do?

The Senate has also used the alternative of censure to discipline members considered to have crossed the line. Censure votes have succeeded nine times, most recently against David Durenberger, a Minnesota Republican, in 1990. Durenberger was censured over expense reimbursements and acceptance of outside payments and gifts. He left the Senate at the end of that term.

In 1979, Democrat Herman Talmadge of Georgia was censured for improper financial conduct and defeated for re-election the following year.

In 1967, Democrat Thomas Dodd of Connecticut was censured for using his office to convert campaign funds for personal use. He was denied his party's nomination for re-election in 1970, lost his bid to stay in office as an independent and died the following year.

Perhaps the most celebrated use of censure came late in 1954 when the Senate censured Wisconsin Republican Joseph R. McCarthy. Officially, McCarthy was censured for noncooperation with a committee investigating his conduct.

But McCarthy had for years been a national celebrity and source of controversy with his claims of communist infiltration in the federal executive branch, including in the Army. After his censure, McCarthy was largely shunned by his Senate colleagues and gradually withdrew from the public eye. He died just 2 1/2 years later at the age of 48.

Why would the person in charge of Republican Senate campaigns be calling for this?

In the present case of Alabama's Moore and the Washington Republican leadership, it was notable that while other others called on Moore to withdraw from the race, the call for expulsion came from Gardner, the campaign chief.

Given his rightful focus on his campaign task, Gardner might be expected to suggest something as rare as expulsion as a way of distancing himself and his party from the toxic attention generated by Moore.

Gardner's greatest fear is not losing one seat in Alabama but having his candidates in dozens of other states tainted by Moore, his record, his reputation and all the stories that would be written about him as a senator.

In 2012, Republicans everywhere were badgered for answers about Todd Akin, a GOP member of Congress and their party's Senate nominee in Missouri, who said women "had a way of shutting things down" to prevent pregnancy "in cases of legitimate rape."

While Republicans have only a handful of seats to defend in 2018, several are potentially vulnerable. One is in Nevada, which voted for Democratic presidential nominee Hillary Clinton in 2016, and two are in states where the incumbent is retiring (Arizona and Tennessee).

And Gardner has the far larger task of recruiting, promoting and funding candidates in two dozen other states whose current senators are Democrats or independents. Copyright 2019 NPR. To see more, visit https://www.npr.org.