Rep. Mark Kirk (R-IL) is an ambitious politician. He's a ladder climber. He's not well-liked by fellow Republicans in the state because of it. (They would have much preferred to see Rep. Peter Roskam run for Senate, but Roskam enjoys his job and wants to be House Speaker some day.)  So think about what happens if Kirk gets elected in the fall. He's facing Alexi Giannoulias, the state treasurer. Absent a major change to the dynamics of the race, Kirk could win it, even though the state trends Democratic.  Giuannoulias's strategy, as exemplified in this web video, is to try to show voters that Kirk isn't the moderate he claims to be -- that he's basically a naked would-be emperor who will don whatever clothing happens to fit his instincts at the moment.
If Kirk wins the seat, he's instantaneously the biggest name in the GOP.  The seat, you'll remember, was Barack Obama's seat. Kirk would be bigger than Massachusetts's lion killer Scott Brown, bigger than the presidential candidates for a while, and he can be a kingmaker.  

He'll have a huge donor list, he'll own Obama's seat, and then he's faced with a choice. Does he moderate himself truly, work in a bipartisan way and be a leader in the Senate.  Or, does he go with immediate ego gratification and position himself to be on the vice presidential short list for 2012? If Kirk doesn't want to run against in 2016, he can bank on the fact that he'll either be on the veep short-list then, or he'll be a bona fide presidential contender in his own right.

Basically, he won't make the "mistake" that Mitt Romney did.  He won't cooperate with Democrats, getting any blemishes on his record. 

The above argument is a variant of what Illinois Democrats are sending to the White House political team. They insist that a relatively mild engagement in the race -- a fundraising e-mail -- could provide the divine intervention that Giannoulias needs to move beyond his ties to his family's failed bank.

The White House's response is that the mess that is the Democratic Party is not Obama's fault, and he feels disinclined to fix it. First, Giannoulias must prove that he's capable of rising about his scandal. And THEN the White House might get involved. 

This says something about party building. Obama's a build-from-the-ground up guy. Given the political environment, Obama Democrats -- think Michael Bennet from Colorado -- aren't terribly popular. Obama's not creating a cadre of candidates who think like him or talk like him; Bill Clinton tried to clone himself using a Democratic Leadership Council template. So far, there IS no Obama template.