Via Chris Cillizza:

In Indiana, Rep. Joe Donnelly is running a television ad in which he details his generally conservative stance on immigration while images of Obama and Pelosi are shown on screen. “That may not be what the Washington crowd wants, but I don’t work for them,” Donnelly says in the ad. “I work for you.”
Rep. Travis Childers, who represents a district in northern Mississippi where Obama won just 38 percent of the vote in 2008, takes a similar approach in his TV advertising — promoting the fact that he has “voted against every big budget” since winning a special election two years ago.
Even some Democratic candidates who are being heavily touted by the White House appear determined to keep the president at arm’s length. Shortly after Obama played a lead role in helping Sen. Michael Bennet defeat former state House speaker Andrew Romanoff in a Democratic primary fight last Tuesday, Bennet was asked whether he would want the president to campaign with him this fall. “We’ll have to see,” Bennet told ABC’s George Stephanopoulos — a response well short of a ringing endorsement of Obama’s political standing.