Mark Kirk, the Republican Congressman from Illinois’ 10th District who voted for Pelosi’s Cap-and-Tax bill, has begun telling GOP grasstops in his home state that he’s running for Senate. Kirk will try to unseat incumbent Democrat Roland Burris, if the man who took Obama’s seat survives his own part primary.

One interesting development to watch for: will the NRSC and other national Republican organizations get behind a candidate who voted for a national energy tax that Republicans would like to use to hang their Democrat opponents. National party figures do have a recent history of supporting moderates even when they break from the party on major issues (see Charlie Crist).

Kirk’s potential bid has been championed by state and national party leaders. They view his voting record in Congress over five two-year terms, siding with the party often but breaking away on environmental and social issues, as a perfect mix to win statewide office in the Democratic state.

He already has an endorsement from former Illinois Gov. Jim Edgar, who led the state in the 1990s.

“He attracts votes in large percentages from both independents and Democrats,” Edgar said. “He is the moderate kind of Republican that can win statewide in Illinois.”

Here we go again.

Here’s how the Democrat landscape is shaping up:

On the Democratic side, contenders could include Illinois Treasurer Alexi Giannoulias and Merchandise Mart boss Chris Kennedy, both of whom are hoping for support from President Barack Obama. Giannoulias is an Obama friend and U.S. Sen. Ted Kennedy – Chris Kennedy’s uncle – was an early and crucial supporter of the Illinois Democrat’s presidential ambitions.

Incumbent Roland Burris may also make a run, but he has been under a cloud since his appointment by Rod Blagojevich after his arrest on corruption charges. A U.S. Senate ethics inquiry into Burris’ interactions with Blagojevich before that appointment remains ongoing.

Mark has more than $1 million in the bank for the Senate bid, which is a great start but far shy of the $15-20 million or more he’ll need for a hotly contested Senate race with implications of breaking the 60 vote hold Democrats have in the Senate.

Update: Chris Cilizza reported this afternoon that Kirk had decided not to run, but his office says otherwise.