Obama to Campaign for Sestak in Pennsylvania

President Obama is heading to Pennsylvania to help Democratic Rep. Joe Sestak's bid for the Senate.

The Sestak campaign said Friday that the president will appear at a Sept. 20 fundraising event in Philadelphia for the Democrat. Sestak is locked in a tight race against Republican Pat Toomey, a businessman and former House member.

Sestak defeated Obama-backed Sen. Arlen Specter, a longtime Republican who became a Democrat rather than face Toomey in a GOP primary. Organized labor and the White House both were embarrassed when Sestak won the Democratic nomination.

Since then, outside groups have been airing a string of negative television commercials against the candidates.