WASHINGTON (AP) — Rick Santorum has won Alabama’s Republican presidential primary. The former Pennsylvania senator edged rivals Newt Gingrich and Mitt Romney to capture the Deep South state.

Mississippi remains a close race, with Santorum edging slightly ahead. The state is still too close to call.

Evangelicals played a critical role in both states’ vote. Roughly 4 in 5 voters who were surveyed in an exit poll called themselves born-again or evangelical in both Alabama and Mississippi.

Update: Big night for Santorum.

(National Journal) — Republican presidential candidate Rick Santorum won the Alabama and Mississippi primaries Tuesday night, a double triumph that bolsters his claim to be the party’s chief alternative to Mitt Romney and increases the pressure on Newt Gingrich to drop out of the race.

Mitt Romney, the former governor of Massachusetts, fell short despite late predictions of a possible upset — and potential knockout blow — in a part of the country far from his comfort zone. His loss guaranteed the fractious GOP primary process will continue for now.

The results could be lethal for former House Speaker Gingrich, who represented suburban Atlanta in the House and had counted on a strong showing in the South. Gingrich on Tuesday vowed to stay in the race until the August convention in Tampa no matter what the outcome of the primaries, but pressure on him to drop out by Republican leaders was mounting even before his latest loss.