One point frequently raised in the coverage of Representative Anthony D. Weiner is that David Vitter, the Lousiana Senator who in 2007 acknowledged that he was a longtime client of a Washington-based prostitution service, did not resign his seat. In fact, Mr. Vitter won re-election with 56.6 percent of the vote last November.
It’s not clear, however, that Mr. Vitter paid no price at all with his constituents. Mr. Vitter’s 19-percentage point margin of victory over his Democratic opponent, Representative Charlie Melancon, was quite solid. But incumbent Republican senators in five other Southern states — Alabama, Georgia, North Carolina, Oklahoma and South Carolina — won their elections by an average of 28 percentage points. (That’s what happens when you’re an incumbent in a very Republican part of the country in a very Republican year.)
Perhaps a better comparison is to look at Mr. Vitter’s results against those of the four Republican incumbents in the House of Representatives who ran against Democratic opposition in Louisiana last year. These were the incumbents in the First, Second, Fourth and Sixth Congressional Districts. (Louisiana’s Third Congressional District had no incumbent, while the Republican incumbents in the Fifth and Seventh Districts did not have a Democratic challenger.)
Based on precinct-by-precinct returns, Mr. Vitter won a total of 54.5 percent of the vote in these four Congressional districts. By comparison, the Republican incumbents for the House drew a collective 62.6 percent of the vote.
In other words, Mr. Vitter underperformed the Republican incumbents by about 8 percentage points — although some of these votes went to third-party candidates rather than to Mr. Melancon.
We cannot know for sure whether this was because of Mr. Vitter’s sex scandal rather than some other factor (Mr. Melancon was not a bad challenger, for instance). And no two sex scandals are quite alike.
But a recent paper by Nicholas Chad Long of St. Edward’s University suggests that Mr. Vitter’s experience might be fairly typical. The study, which examined United States Senators running for re-election from 1974 to 2008, found that scandals involving immoral behavior cost the incumbent an average of 6.5 percentage points.
Mr. Weiner won re-election with 60.8 percent of the vote last year, so an 6.5-percentage point penalty would have left him with enough votes for a majority. On the other hand, Mr. Weiner drew a relatively obscure challenger last year in Robert L. Turner, a businessman with no electoral experience. His district — unlike almost all others in New York City — is only a few points more Democratic than the country as a whole, so a stronger Republican opponent might give him quite a few problems. (Mr. Long’s study found that scandal-plagued incumbents draw more qualified challengers.)
The good news for Mr. Weiner? Mr. Long’s study found that Republicans may pay a bigger price than Democrats do. Combining all types of scandals — involving everything from sexual infidelity to financial impropriety — Republican incumbents lost an average of 7.7 percent of the vote, while Democrats lost 4.9 points.