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Rick Santorum announced on Tuesday that he is withdrawing from the presidential campaign, citing the recent hospitalization of his 3-year-old daughter, Bella, as his primary motivation. Although Bella, who suffers from a rare genetic disorder, was released from the hospital on Tuesday and is back with her family, Santorum said that his role as a parent pushed him to make the decision.

"This was a time for prayer and thought over this past weekend," he said at a press conference in Gettysburg, Pa., going on to say that the decision to join the presidential race in the first place was motivated by similar factors. "We were very concerned about our role as being the best parents we possibly could to our children, in making sure that they had a country where the American dream was still possible."

After recounting stories of supporters that he met across the country on the campaign trail, from a tearful fighter pilot who feared the direction of America's foreign policy to a young man with spina bifida who felt that Santorum was the candidate who best understood the needs of people with disabilities, he said that it was their voices that truly fueled his campaign.

"People asked how were we able to come from nowhere," he said. "It's because I was smart enough to figure out that if I understood and felt, at a very deep level, what you were experiencing across America and tried to be a witness to that ... your voice could be heard and miracles could happen. And so it did, miracle after miracle. This race was as improbable as any race that you will ever see for president."

Despite the end of his campaign, Santorum said that he will continue to advocate for the issues on his platform, including how to confront "the scourge of Iran" and "the family and the dignity of human life," just in a different format. "We are not done fighting," he said.

If the Republican primary race wasn't already all but over after Mitt Romney won a trio of contests last week in Washington, D.C, Maryland and Wisconsin, Santorum's exit virtually assures it.

In a statement, Romney congratulated his top opponent. "He has proven himself to be an important voice in our party and in the nation," wrote Romney. "We both recognize that what is most important is putting the failures of the last three years behind us and setting America back on the path to prosperity."

Cynthia Gordy is The Root's Washington reporter.