Speaking to a packed firehouse in Whitpain Township, Giuliani said limited government and reduced taxes will help businesses grow and help the nation's economic recovery.
"Toomey has led the fight for fiscal responsibility," Giuliani said. "He'll be a leader in straightening out the economy of this country."
Toomey is battling Democratic Rep. Joe Sestak, who beat five-term Sen. Arlen Specter in the primary. The candidates are set to debate Friday evening in Pittsburgh, their last scheduled debate before the Nov. 2 election.
Giuliani, who was lauded for his leadership after the 9/11 terrorist attacks, said the current administration "has weakened our response to Islamic extremism." He derided Sestak's support for holding terrorist trials in federal civilian courts.
With the race so close, national party committees and others are pouring millions of dollars into the race.