No matter what time of year it is, (be it an American election or otherwise) political sex scandals span both the Democratic and Republican parties. From Political Johns to lowly adulterers, the two are pretty even in terms of sex scandals since 1976. Democrats have edged ahead in recent years though! This is a politician list of sex scandals. For the other side of political sex scandals see the Republican list.
http://www.ranker.com/list/democrat-sex-scandals/web-infoguy,
Anthony D. Weiner
Posted a Twitter photo to Gennette Cordova, a 21-year-old college student in Seattle, of himself in only a grey underwear with a very distinctive outline (hint, hint).
UPDATE: In the aftermath of this scandal, Weiner went on a public apology tour, gained the public's confidence back and started his bid for Mayor of New York. Somehow, he was actually leading the polls in early summer 2013. In late July, it was uncovered that he was still sexting with young 20-something females even while he was appearing publicly apologizing for it, under the pseudonym Carlos Danger.
Antonio Villaraigosa
Affair with a television reporter.
Bill Clinton
Affair with intern Monica Lewinsky.
David Paterson
Admitted that both he and his wife had extramarital affairs
David Wu
Accused of sexually assaulting an unnamed 18-year-old California woman.
Eliot Spitzer
Involved in prostitution scandal.
John Edwards
Had an affair with a campaign employee while running for President.
Has now also admitted to fathering an illegitimate child (1.2010) by the same woman, a campaign videographer.
Kwame Kilpatrick
Text messaging sex scandal
Marc Dann
Attorney General of Ohio, had an affair with a staffer.
Paul Morrison
Affair with administrative staffer while Attorney General of Kansas, pressured her to reveal information about Kansas D.A.