The leading Republican presidential hopefuls focused their campaigns on the Deep South, with polls showing a tight three-way contest in tomorrow’s pivotal primaries in Alabama and Mississippi.
The two states have taken on unexpected importance in the race to find a challenger to President Barack Obama in November.
For Rick Santorum, a strong showing in both states could enable him to finally establish himself as the main challenger to front-runner Mitt Romney.
Mr Santorum, a former Pennsylvania senator, nudged rival Newt Gingrich, the former speaker of the House of Representatives, to step aside, arguing a head-to-head contest between himself and Mr Romney should “occur sooner rather than later”.
Both Mr Santorum and Mr Gingrich are attacking the more centrist Mr Romney from the far right of the political spectrum and have found significant support from the conservative Republican base.
A defiant Mr Gingrich predicted victories in both southern states, where losses would effectively end his chances.
Mr Gingrich has banked his waning prospects on an all-Southern strategy. His lone primary wins have been in South Carolina and Georgia, a state he represented in Congress for 20 years.
A win for Mr Romney in Alabama, where polling shows a tight contest among him, Mr Gingrich and Mr Santorum, could all but close out the Republican nominating contest.
The former Massachusetts governor has built a substantial delegate lead against his rivals but has failed so far to win a state in the Deep South, home to the Republican Party’s most conservative and religious voters.
Mr Romney has built his lead in delegates to the party’s national nominating convention in August largely because Mr Santorum and Mr Gingrich have split the conservative vote.
That enabled Mr Romney to edge out Santorum by a few percentage points in closely fought primaries in his home state of Michigan and the key industrial state of Ohio.