Kentucky Lt. Governor Dan Mongiardo says he'll seek the Democratic nomination for the U.S. Senate seat currently held by Republican Jim Bunning.Mongiardo, who was narrowly defeated by Bunning in the 2004 race, made the announcement Monday in a written statement.Bunning has repeatedly said he'll seek re-election in 2010, although he has raised very little campaign money.Other Democrats who are considering a run for the office include Attorney General Jack Conway and State Auditor Crit Luallan.