Feingold and his wife, Mary, issued a joint statement through the Democrat's Senate office saying they have decided to end their marriage of 14 years.

Feingold built a national following among progressives with his work on campaign finance reform, and by casting the only vote in the U.S. Senate against the Patriot Act.

Several Web sites have sprung up urging Feingold to run for president, and he hasn't ruled out a race.