WASHINGTON — Rick Santorum was projected to sweep two southern states in Republican primaries, all but burying Newt Gingrich’s chance for the nomination and complicating Mitt Romney’s status as frontrunner.

Santorum, the former Pennsylvania senator who emerged from last place in polling as recently as December to become the conservative challenger to Romney, scored 33 percent of the vote in Mississippi, with 96 percent of votes counted, and 35 percent of the vote in Alabama, with 79 percent of votes counted.

Gingrich, the former U.S. House of Representatives speaker, came in second in both states, with 31 percent in MIssissippi and 30 percent in Alabama, and Romney came in third with 30 percent and 28 percent, respectively.

Rep. Ron Paul (R-Texas) came in a distant fourth in both races; he had hardly campaigned in the states.

Romney, the former Massachusetts governor who has tried during the contest to shuck his reputation as a moderate, campaigned hard for a victory in a bid to prove he could win in conservative southern states. He is leading susbtantially in delegates but his path to the nomination has been far from smooth as conservative candidates continue to mount substantive challenges.

Gingrich had suggested that if he failed to win in these states his campaign was in trouble, predicated as it was on wins in southern states.

If Gingrich leaves the race, campaign watchers will look to see whom his main backer, casino magnate Sheldon Adelson, decides to support.

Adelson and his wife Miriam twice salvaged Gingrich’s campaign with huge cash infusions; Gingrich and Adelson have been friends since the 1990s, in part because they share hawkish pro-Israel positions.

Romney has the backing of much of the Jewish Republican establishment, having attracted both the bulk of Jewish donors and advisers.

His appeal to Jews is based partly on his moderation and his ability during his 2003-2007 governance of Massachusetts to appeal to liberals and independents.

Additionally, he and his wife, Ann, have referred in talks to Jewish groups to their Mormon faith, likening themselves to Jewish Republicans who have pushed for prominence in a party that still draws much of its support from a Protestant base.

Santorum and Romney have both battered President Obama for what they depict as his hostility to Israel and his fecklessness on dealing with Iran, and both say that the will repeal much of the heath care reform package the president passed.

Some of Santorum’s domestic policies, including statements suggesting that a “Jesus guy” is most suitable for the presidency, have alarmed some Jewish groups.