Latest setback for GOP that has suffered losses of at least 13 Senate seats in the past 2 elections & saw Sen. Specter defect to Democrats in April.

From The Washington Post:

Sen. John Ensign (Nev.), considered a rising star in the Republican Party, yesterday acknowledged an extramarital affair with a former campaign staffer who is married to one of the lawmaker's former legislative aides.

The news was the latest setback for a party that suffered losses of at least 13 Senate seats in the past two elections and saw Sen. Arlen Specter (Pa.) defect to the Democrats in April. Any further instability in their ranks is unwelcome news for Republicans, who viewed Ensign as a telegenic communicator who could deliver the conservative message on political talk shows in a congenial matter.

He does not face reelection until 2012 and had taken preliminary steps to explore a run for the White House that year, making a trip three weeks ago to Iowa, the first testing ground on the presidential primary calendar.