Updated

GOP presidential hopeful Rick Santorum is headed back on the campaign trail after his sick 3-year-old daughter made a "miraculous turnaround" Sunday.

Santorum cancelled many campaign events this weekend after he returned home to find his daughter Bella hospitalized with pneumonia and "not doing well."

However, Santorum told Florida voters during a call Sunday that his daughter had turned a corner, and he would be heading back to his campaign.

He described the situation as a "very, very tough night last night" but said by late Sunday Bella was "alert and back to her own beautiful, happy girl."

"It's been a very hectic 36 hours," Santorum said. "Life in the Santorum family has dramatically improved since the late afternoon."

He said doctors hope she can go home in the next few days.

After hearing of Bella's illness, rivals and partisans set down their talking points and instead offered prayers and well wishes to the Santorum family.

"Ann and I send prayers and best wishes for Bella's good health to Rick and Karen Santorum and their entire family," said Republican presidential primary frontrunner Mitt Romney.

"Lift up prayers for Bella and the Santorum family," said Newt Gingrich backer and former GOP rival Rick Perry.

"Thank you, Rick and Karen Santorum, for living the Christ-like example of sacrifice and right priorities," wrote Sarah Palin on Facebook on behalf of her family. "Nothing is more precious or important than the life of an innocent child. Our prayers are with Bella, a perfect child in an imperfect world. God bless the beautiful Santorum family."

"Let me also add my prayers and thoughts for Senator Santorum and his child. I have gone through problems with a child and my heart goes out to him and his family," said President Obama's adviser David Axelrod at the start of an interview on NBC's "Meet the Press," a show on which Santorum had been scheduled to appear but canceled. As an infant, Axelrod's daughter sustained brain damage from a series of massive epileptic seizures.

Bella, whose full name is Isabella, has Trisomy 18, a genetic condition caused by the presence of all or part of an extra 18th chromosome. Half of infants born with the disease don't live past their first week and a smaller percentage live to their teens.

Bella was hospitalized with pneumonia in both lungs, a campaign aide said.

Elizabeth Santorum, 20, stepping up a surrogate for her father in Florida on Sunday, said the family is coping.

"You know we do what we do as a family, you know we stick together and you know, we get through and we're hanging in there," she said.

Santorum has frequently discussed his daughter's condition on the trail, saying that Bella's birth is an every day example of the value of life.

"I have a little girl who's 3-and-a-half years old," he told Christian conservatives in Iowa before winning that lead-off contest.

"I don't know whether her life is going to be measured -- it's always been measured -- in days and weeks. Yet here I am. ... because I feel like I wouldn't be a good dad if I wasn't out here fighting for a country that would see the dignity in her and every other child."

In October, Santorum missed one of Bella's surgeries to participate in a debate and told the audience that he planned to take an all-night flight home from Las Vegas to be with her.

"I look at the simplicity and love she emits," Santorum said in a web video his campaign released after his scheduling drew questions, "and it's clear to me we're the disabled ones."

Santorum canceled his Sunday show appearance and a stop at a Miami church on Sunday to be with his daughter at the Children's Hospital in Philadelphia. Campaign spokesman Hogan Gidley said Santorum hopes to return to a campaign schedule soon.

Florida's presidential primary is on Tuesday. Asked whether he had any conversation with Santorum, Newt Gingrich, who is competing with Santorum for the social conservative vote that Gingrich says combined would outnumber Romney's support, said he had not discussed asking him to drop out.

"As you, I think, may know, his daughter went into the hospital last night so this would be a totally inappropriate time to do anything like that. Rick's going to get a decent vote tomorrow -- on Tuesday -- I have no doubt the two of us are going to collectively outscore Romney. And at that point it might be a pretty good conversation."

The Associated Press contributed to this report.