"Hello, Pat? This is Barack Obama," a voice said.

"Who the hell is this?" Gillespie responded.

But it really was the presidential candidate, phoning the influential labor leader in anticipation of a Building Trades Council endorsement meeting the next day.

Obama's 15-minute chat with Gillespie is just one measure of the fact that the smoldering Pennsylvania campaign efforts of Obama and Hillary Clinton are about to flare to life.

Both campaigns will open offices in Philadelphia and Pittsburgh in coming days. Each will expand what have been skeleton campaign staffs, recruiting local pros and bringing in national operatives to prepare for what could be the decisive battle in the Democratic presidential primary campaign.

If Clinton wins key primaries in Texas and Ohio a week from tomorrow, Pennsylvania will host a seven-week dogfight for the last major prize before the Democratic convention, with both campaigns pouring everything they have into the effort.

"Four million people will come here that Wednesday morning," veteran Democratic media consultant Neil Oxman said. "Every heavyweight in both campaigns will be here."

Here's a look at some of the forces already in the field and reinforcements soon arriving for the mother of all Pennsylvania primaries:

Heavyweight supporters

 

Her supporters include Gov. Rendell, Mayor Nutter, state party chairman T.J. Rooney, Congresswoman Allyson Schwartz, Congressman Joe Sestak and others.

Many are superdelegates, and all have influence with their own network of donors and activists.

Obama has fewer big names, but seems to have some momentum. Congressmen Chaka Fattah and Patrick Murphy have been on board for a while, and the campaign recently picked up superdelegates Carol Ann Campbell and Philadelphia Councilman Jim Kenney, and Leon Lynch of western Pennsylvania.