US voters in 10 states are set to go to the polls in primary and caucus contests, as the battle to win the Republican Party’s presidential nomination continues.
Alaska, Georgia, Idaho, Massachusetts, North Dakota, Ohio, Oklahoma, Tennessee, Vermont and Virginia are all up for grabs on a day dubbed "Super Tuesday" that has traditionally been decisive in determining who goes on to claim the nomination.
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The sheer number of states in play Tuesday, with their diverse demographics and political leanings, could break open a candidate's pathway to the nomination, or spell the end of a failing campaign.
Super Tuesday essentially ended the Republican nomination battle in 2008, when Mitt Romney capitulated and Senator John McCain went on to become the nominee.
Four years later, Romney is the frontrunner and could possibly seal the nomination on Tuesday. However, close behind is Rick Santorum, still hoping to pull off a stunning upset by drawing on growing support among the Republicans' conservative base. Newt Gingrich and Ron Paul are also still in the race.
But many analysts predict that no clear winner will emerge.
"I'm not sure Tuesday means that much other than more of the same," said veteran strategist Neil Oxman, co-founder of The Campaign Group.
All eyes on Ohio
"What's going to happen is, Santorum is going to do well enough to continue," while Romney will emerge from Super Tuesday as "the favourite, but not the overwhelming favourite," Oxman told AFP news agency.
With some 437 delegates to August’s Republican National Convention at stake - nearly 40 per cent of the 1,144 needed to secure the nomination - Romney and Santorum have been criss-crossing the country in a frenzy of campaigning.
Romney got a boost going into Tuesday's votes with a win in the Washington state caucuses, but that contest was non-binding.
Romney, Santorum and Gingrich all spent Monday campaigning in Ohio, which for decades has served as a "bellwether" for the general election, voting for the eventual winner.
One important factor is Gingrich, who is hoping to inject some new momentum into a flagging campaign. He is polling ahead in Georgia, the state he served in Congress for 20 years, and which has Tuesday's largest haul of 76 delegates.
Gingrich has been vying with Santorum to be the conservative alternative to Romney, but has faltered since a January win in South Carolina.
With the back-and-forth competition still undecided, some are starting to speculate about a possible brokered convention when the Republican Party gathers to select their candidate later this year.
If no one is able to win the 1,144 delegates needed, then the floor could open to potential candidates not currently in the race.
Al Jazeera’s Alan Fisher in Washington blogged about possible outsiders who could come into the race. Two popular Republican politicians, former Alaska governor Sarah Palin, who ran alongside McCain in 2008, and former Florida governor Jeb Bush, the younger brother of former president George W. Bush, are two potential candidates.
“Though anyone who predicts what can happen in this latest campaign may be misguided, the fact that Republicans still hanker for someone else shows deep dissatisfaction with the choice they have before them,” Fisher said.
“But at this late stage, it’s likely to be the only choice they’ll have.”