"People say you're being outspent [by Romney] and everybody's talking about all the [delegate] math, and that his race is inevitable. Well, for someone who thinks this race is inevitable, [Romney]) has spent a whole lot of money."
Gingrich congratulated Santorum and said "the elite media's efforts to convince the nation Mitt Romney is inevitable just collapsed."
"The fact is in both states the conservative candidates got nearly 70 percent of the vote and if you're the front-runner and keep coming in third, you're not much of a front-runner," Gingrich said.
CNN said with 79 percent of Alabama's precincts reporting Santorum had 152,061 votes (35 percent) to 128,812 (30 percent) for Newt Gingrich and 123,839 (28 percent) for Mitt Romney. Ron Paul was fourth with 21,768 votes (5 percent).
In Mississippi, the secretary of state's office said with 1,793 of 1,889 precincts (94.9 percent) reporting, Santorum led with 89,880 votes (32.9 percent) to 85,626 (31.3 percent) for Gingrich and 82,904 (30.3 percent) for Romney. Paul, again, was fourth with 12,107 votes or 4.4 percent.
Mississippi's secretary of state said voter turnout was light in the GOP primary, and there were reports that some precincts opened late.
Secretary of state spokeswoman Pamela Weaver told the Jackson (Miss.) Clarion-Ledger the office had received 50 calls reporting voting problems, including delays of as much as 2 hours in opening polling locations in Hinds and Claiborne counties.
Public-opinion polls had Santorum, the former Pennsylvania senator, in a tight three-way race heading into the two southern states. In Alabama, he was in a statistical dead heat with Romney, a former Massachusetts governor, and Gingrich, a former House speaker from Georgia.
In Alabama, where 50 Republican National Convention delegates were at stake, a Public Policy Polling survey showed Romney ahead with 31 percent of the vote, followed by Gingrich with 30 percent, Santorum with 29 percent and Paul, the Texas congressman, with 8 percent.
A separate PPP survey in Mississippi, whose primary had 40 delegates at stake, showed Gingrich ahead with 33 percent of the vote, Romney with 31 percent, Santorum with 27 percent and Paul with 7 percent.
Both polls were conducted Saturday and Sunday through automated phone interviews. The margin of error was 4 points in Alabama and 3.8 points in Mississippi.
The Hawaii and American Samoa Republican caucuses were also being held Tuesday, with Romney widely expected to win those contests.
Romney, who celebrated his 65th birthday Monday, suggested to Alabama supporters a Southern primary victory would be the perfect birthday present.
"Thanks so much for giving me this birthday present. Hopefully, I can unwrap it tomorrow," he told a crowd at Mobile's Whistle Stop restaurant Monday.
He later told the Fox News Channel despite what Santorum told NBC's "Meet the Press" Sunday, "We're closing the deal, state by state, delegate by delegate.
"I guess two, two-and-a-half times as many delegates as he has, about the same number of state advantages that he has, many more Republican voters than he has," Romney said, comparing his status with that of Santorum.
Going into the day's primaries, Romney had 454 delegates, Santorum 217, Gingrich 107 and Paul 47. A candidate must accumulate 1,144 delegates by the August GOP convention in Tampa, Fla., to clinch the nomination.