Santorum off trail, Romney pulls attack ad

Mitt Romney's presidential campaign pulled an attack ad set to air in Pennsylvania targeting Rick Santorum, responding to the Republican rival's decision to suspend politicking after the hospitalization of his daughter.

"Stations will comply with this request as soon as they are technically able," Romney spokeswoman Andrea Saul said.

The campaign asked the stations to replace the negative spot with a pro-Romney commercial praising his record as former governor of Massachusetts.

The $2.9-million ad buy was set to start Monday, with a spot focusing on Santorum's "historically embarrassing" loss in Pennsylvania in his 2006 bid for a third U.S. Senate term. In a midterm election in which Republicans lost control of both chambers of Congress, Santorum was defeated by 18 percentage points by Democrat Robert Casey.

"We fired him as senator, why promote him to president?" a narrator in the Romney-sponsored ad asks.

Both men plan to hold events Tuesday, with Romney campaigning in Delaware and Santorum scheduled to participate in a religious forum with Christian broadcaster James Dobson in Lancaster, Pa.

Santorum is pushing to regain momentum from front-runner Romney in the Republican presidential nomination battle.

While Santorum has vowed to remain a candidate into May, campaign aides have said winning Pennsylvania's April 24 primary is crucial to his political survival. Polls show a close race.

Santorum took several days off from the campaign trail after announcing Friday that his 3-year-old daughter, Bella, was hospitalized. She has a rare genetic disorder known as Trisomy 18, and her survival has defied the odds for those afflicted with the condition.