A new ad from the campaign of Rep. Joe Donnelly (D-Ind.) takes a major shot at House Speaker Nancy Pelosi (D-Calif.).

Donnelly touts his opposition to cap-and-trade in the 30-second spot, with the ad's narrator deriding the proposal as "Nancy Pelosi's energy tax," and calling Donnelly "Indiana's most independent congressman." 

It's one of the most overt attempts this cycle from any House Democrat to distance themselves from Pelosi. 

Donnelly faces state Rep. Jackie Walorski (R) in the fall. Walorski won the backing of former Alaska Gov. Sarah Palin on Wednesday and is on the National Republican Congressional Committee's list of "Young Guns."