Obama state HQ opens Thursday in Phila.

President Obama's re-election campaign is gearing up in Pennsylvania, a crucial state that he carried in 2008 and that is central to his strategy to win in 2012.

Supporters are invited to celebrate the opening of the state headquarters Thursday in Center City at an open house from 5 to 8 p.m. On the bill: musical entertainment, state Sen. Anthony Williams (D.,Phila.) and senior Obama for America officials, who will describe the campaign's plans for Pennsyvlania.

The address is 42 S. 15th Street, and the office is on the 16th floor.