GETTYSBURG, Pa. - Rick Santorum quit the U.S. presidential campaign Tuesday, clearing the way for Mitt Romney to claim the Republican nomination.

Santorum, appearing with his family in his home state of Pennsylvania, told supporters the race for him was over, but the fight to defeat President Barack Obama in November's general election would go on.

He made no mention or endorsement of Romney, whom Santorum had derided as an unworthy standard-bearer for the Republicans. The former Pennsylvania senator stressed that he'd taken his campaign farther than anyone expected.

"We are going to continue to go out there and fight to defeat President Barack Obama," Santorum declared.

Santorum spoke with Romney ahead of his announcement, a Republican source close to the campaign said.

Romney congratulated Santorum on his campaign, calling him an "able and worthy competitor."

The delegate totals from state-by-state voting told the tale of Santorum's demise. Romney has more than twice as many delegates as Santorum and is on pace to reach the number needed to clinch the Republican nomination -- 1,144 -- by early June. Still in the race, but not considered a factor, are former House Speaker Newt Gingrich and Texas Rep. Ron Paul.

Santorum had been hoping to hold out through the primary in Pennsylvania on April 24, but he decided to fold up after spending the weekend at home with his severely ill 3-year-old daughter, Bella.

Santorum, a feisty campaigner who took everyone by surprise with his win in Iowa's leadoff caucuses, ran on his conservative credentials. But he was hobbled by a lack of money and organization.

Santorum stressed the improbable accomplishment of the past year, saying that "against all odds, we won 11 states, millions of voters, millions of votes."

He said that while Romney was accumulating more delegates, "we were winning in a very different way. We were touching hearts" with his conservative message.

In a statement, Romney said Santorum "has proven himself to be an important voice in our party and in the nation. 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."