Maine Democrats Hope to Replace Platner as Senate Nominee. Has That Ever Worked?

Graham Platner, the Democratic nominee for Senate in Maine, suspended his campaign on Wednesday in the wake of a rape allegation he denies. It’s now up to the Maine Democratic Party to find a replacement candidate.

How rare is this? Out of more than 500 Senate races over the past 30 years, we identified only nine previous instances when a major party replaced its nominee.

Only two of those nine races ended in a win for the replacement candidate, though the circumstances varied widely. Often the replacement candidate’s party had little chance of winning anyway. A substitution in a closely contested race, like this year’s in Maine, is even more rare.

One of the lopsided races cleared the way for a new political career: Barack Obama beat a replacement Republican candidate in Illinois by more than 40 points in 2004. Mr. Obama’s initial opponent, Jack Ryan, dropped out after unsealed divorce papers revealed his ex-wife’s accusations that he had taken her to sex clubs. The candidate who replaced Mr. Ryan, Alan Keyes, had never lived in Illinois.

One of the two winning substitutes during this period was Tim Hutchinson, a Republican who replaced Mike Huckabee on the ballot in Arkansas in 1996. Mr. Huckabee, then the lieutenant governor, abandoned his Senate nomination to become governor after Gov. Jim Guy Tucker resigned. Mr. Hutchinson won the Senate seat by five percentage points, flipping the open seat for Republicans.

The other successful swap was in New Jersey in 2002. An incumbent Democrat, Robert Torricelli, dropped his re-election bid after a reprimand from the Senate ethics committee for campaign finance violations. A former senator, Frank Lautenberg, stepped in to fill the nomination and won by 10 points. (After rejoining the Senate, Mr. Lautenberg served until his death in 2013.)

Also in 2002, Senator Paul Wellstone, a Minnesota Democrat who was running for a third term, was killed in a plane crash in late October, less than two weeks before the general election. Former Vice President Walter F. Mondale came out of retirement to take Mr. Wellstone’s place on the ballot, but lost to Norm Coleman by two points.

The most recent competitive Senate race with a substitution was in 2016 in Indiana. Former Representative Baron Hill had won the Democratic primary uncontested, but with Democrats sensing a chance to retake the Senate and looking to flip the seat, Mr. Hill dropped out to make room for a better-known candidate, former Senator Evan Bayh. Mr. Bayh ended up losing the race by almost 10 points, and Democrats fell three seats short of their goal.

The procedures to replace a party’s nominee vary, and occasionally there is not enough time to substitute a name on the ballot. In 2000, Mel Carnahan, a popular Democratic governor, was running for a Senate seat in Missouri. Three weeks before the election, he was killed in a plane crash, and his name was left on the ballot. He won, defeating the incumbent, John Ashcroft. (Jean Carnahan, Mr. Carnahan’s widow, was appointed to the Senate, but later lost in a special election in 2002. Mr. Ashcroft’s next job was U.S. attorney general under President George W. Bush.)

Mr. Platner must formally drop out by Monday in order for another candidate to run, and Maine Democrats have until July 27 to decide his replacement. The state party has said it will hold a nominating convention, but it’s unclear how that will work or if Mr. Platner will attempt to influence the process.

About the data

We compiled data from the Federal Election Commission’s Federal Elections data set, which indicates in footnotes whether candidates were replaced after a primary election. We limited the analysis to Democratic and Republican nominees.