As expected, Kentucky Lt. Gov. Daniel Mongiardo (D) announced today that he will take a second shot at knocking off Sen. Jim Bunning (R-Ky.) after losing his 2004 Senate bid by less than two points.

Mongiardo is the first Democrat to announce his plans to take on Bunning, but he isn’t expected to be the last. State Attorney General Jack Conway (D) and state Auditor Crit Luallen (D) are also considering challenging Bunning.

Luallen, a popular figure in Kentucky, briefly considered challenging Senate Minority Leader Mitch McConnell (R-Ky.) during the 2008 cycle. In 2002, Conway, who was then a cabinet secretary to then-Gov. Paul Patton (D), ran in Kentucky’s 3rd district against then-Rep. Anne Northup (R). He spent more than $1.5 million on the race to Northup’s $3.2 million and lost by just 7,300 votes.

Though Bunning insists he’s running again in 2010, retirement rumors continue to dog the 77-year-old junior Senator from the Bluegrass State. Recent public polls have shown Bunning is less popular than McConnell, who found himself in a closer-than-anticipated race in 2008 that he eventually won by 6 points. Some Capitol Hill GOP insiders have been hinting that Kentucky Secretary of State Trey Grayson (R) might be a more viable candidate than Bunning and could boost the party’s chances of holding the seat.