Vice President Joe Biden will head to Missouri to headline a fundraiser for Secretary of State Robin Carnahan's (D) Senate campaign. The Carnahan campaign confirmed the event will take place, but there's no word yet on exactly when. 

Carnahan, who is locked in a tight race with Rep. Roy Blunt (R-Mo.), already received some fundraising help from the White House in July, when President Obama headlined two events for Carnahan's campaign. 

Blunt outraised Carnahan in the second quarter of the year, hauling in $2.2 million to Carnahan's $1.5 million. Blunt ended the quarter with $4.5 million cash on hand to Carnahan's $3.6 million.

Blunt has worked to tie Carnahan to the president, and used the July event against Carnahan in an earlier attack ad. The president's approval ratings in Missouri are below the 50 percent mark.    

The Carnahan campaign, meanwhile, is working to label Blunt as corrupt, calling the congressman the "very worst of Washington" in an attack ad released earlier this week. 

Outside groups are also spending on the race. The conservative group American Crossroads GPS launched an ad Thursday hitting Carnahan on healthcare. 

-Updated at 5:56 p.m.