Rick Santorum suspends GOP presidential campaign

He said the former senator's campaign was "a testament to his tenacity and the power of conservative principles.

"I am committed to staying in this race all the way to Tampa so that the conservative movement has a real choice. I humbly ask Senator Santorum's supporters to visit Newt.org to review my conservative record and join us as we bring these values to Tampa."

Paul also congratulated Santorum for "running such a spirited campaign" and called himself "the last — and real — conservative alternative to Mitt Romney."

Suspending the campaign allows Santorum to keep paying off nearly $1 million in debt, according to recent Federal Election Commission filings. Those debts include about $500,000 for media consulting and tens of thousands more for telemarking and online advertising, records show.

Other presidential candidates have eventually extinguished their debt and terminated their campaigns. Former Minnesota Gov. Tom Pawlenty officially shuttered his campaign committee on Tuesday, owing as much as a half a million dollars last fall but slowly whittling that figure down.

Associated Press writers Kasie Hunt, Jack Gillum and Nancy Benac in Washington contributed to this report.