Rick Santorum is returning to the campaign trail after a brief hiatus to care for his daughter, Bella, who was hospitalized with pneumonia.

Bella suffers from a rare chromosomal disorder, and her plight has become part of Santorum's image as a family-focused candidate. Santorum's rivals held their fire while Bella was recuperating, with Mitt Romney's campaign choosing to pull a negative ad that focuses on the 17-point loss that ousted Santorum from the Senate in 2006.

A Romney spokesperson said the campaign halted the ad, featured below, out of deference to Santorum.

Bella's illness also prompted a surge in public sympathy. Nearly 2,000 people commented on a post on the candidate's Facebook page announcing she had been taken to the hospital, and more than 4,300 liked a posting announcing she was returning home.

The former Pennsylvania senator will resume campaign activities Tuesday. He is slated to host a rally at a hotel in Gettysburg, Pa., and to speak at Lancaster Bible College in Lancaster. Santorum has said he needs to win in his home state to remain viable as a contender for the Republican presidential nomination, but recent polls show Romney overtaking him. Seventy-two delegates will be at stake in the April 24 contest.