President Obama is headed back to Chicago early next month to headline a fundraiser for Democratic Senate candidate Alexi Giannoulias. The Illinois state treasurer is battling Rep. Mark Kirk (R) for the seat formerly held by Obama. The event is set for Aug. 5.

Giannoulias certainly needs the fundraising help. He raised just $900,000 in the second quarter to Kirk's $2.3 million. Kirk reported nearly $4 million cash on hand at the end of June.

The president's visit is sure to sharpen what is shaping up to be one of the country's nastiest Senate races this year. It also comes against the backdrop of the ongoing corruption trial of former Gov. Rod Blagojevich (D).

The fundraiser should help settle the question of whether the White House is fully invested in Giannoulias. The lack of attention from the White House over the past few months raised questions about just how much confidence the administration had in the Democratic candidate.

But Vice President Joe Biden and Education Secretary Arne Duncan have already made fundraising trips to Illinois for the Giannoulias campaign. White House adviser David Axelrod is also slated to headline an event for the candidate.