Momentum is crucial in the state-by-state race for the Republican nomination, but in the long slog of the US presidential campaign the candidates are also chasing an elusive magic number: 1,144.

That's the threshold of delegates to the Republican National Convention in August that a candidate must win to secure the party's nomination — and almost 40 percent of it will be up for grabs next week on "SuperTuesday."

Super Tuesday essentially ended the Republican contest in 2008, but a more fractured race is expected next week, when 10 states, including key battleground Ohio, vote simultaneously on March 6.

And with more proportional allocation of delegates introduced by the party since the last general election, the Republican race could carry on for

months.

In the complex Republican Party nominating process, delegates are awarded by each state, sometimes on a proportional and/or nonbinding basis, until one candidate reaches the 50-

percent-plus-one mark needed for victory.

Eleven states have held voting contests so far. Romney has won six of them, Santorum four, and former House speaker Newt Gingrich one.

While Romney has won just over 50 percent of the total delegates to date, he has little wiggle room, and more than 100 of the delegates to the convention are Republican National Committee members who can vote for anyone.

Americans appear to be less focused on the specifics of delegates, and more about trends, issues, and electability -- at least for the moment.

But the delegate battle between

Romney and Santorum came under the spotlight Thursday, when a row erupted over how party leaders in Michigan apportioned its 30 delegates after the state's bitterly contested Tuesday primary.

Romney beat ex-senator Santorum by three percentage points in Michigan, but because of proportional distribution, they split 28 of the delegates, 14 each. The party awarded the two delegates both to Romney, prompting Santorum's campaign to

accuse Michigan party insiders of "political thuggery."

Romney on Tuesday is likely to win in states such as Massachusetts, Vermont and Virginia, but he's in a battle royale for Ohio, with 66 delegates at stake, against Santorum, who is ahead in Tennessee (58 delegates) and Oklahoma (43).

If the race continues to be this tight it is possible that no winner will emerge before the Republican National Convention in late August, in which case a victor would have to be decided by backroom brokering among the delegates.

An analyst said he sees about a one-in-four chance of a brokered convention — something that hasn't happened in decades.

"All of us political scientists have our mouths watering; we'd love to see it, "he said.