Washington: Democrat Barack Obama and rival Hillary Clinton battled to a draw on 'Super Tuesday' and John McCain seized command of the Republican race in presidential nominating contests in 24 US states.

In their hard-fought duel for the Democratic nomination, Obama won 12 states and Clinton took eight. Clinton's wins included the key prizes of California and New York on the biggest day of US presidential voting ahead of November's election.

McCain won nine states, including key victories in California and big Northeastern states to take a daunting lead in the Republican race. He captured a huge haul of delegates who select the party's presidential nominee, in part because many of the 21 Republican contests were winner-take-all.

Republican rivals Mitt Romney and Mike Huckabee kept their hopes alive and vowed to fight on. Romney won six states and Huckabee won five.

The mixed outcome in the coast-to-coast voting, with all contenders in both parties scoring at least five wins, appeared certain to prolong the hard-fought nominating races in both parties. A new round of contests in a half-dozen states are slated this weekend and in the coming week.

The Clinton and Obama camps said they expected the count of delegates for the night to be relatively even.

McCain nearly tripled Romney's delegate count, with 378 to Romney's 127 and Huckabee's 91, MSNBC said. That was well short of the 1,191 needed to win the nomination.

McCain, who lost the Republican primary race in 2000 to George W Bush, has struggled to win over conservatives in the party, who have been unhappy with his views on immigration, tax cuts and campaign finance reform.

National exit polls showed more than half of Democratic voters ranked the ability to bring change as the top attribute for a candidate. Nearly one-quarter of Democrats voting in the party's 22 contests ranked experience, Clinton's selling card, as the most important attribute.

About 44 per cent of Republican voters preferred a candidate who shared their values, while one-quarter wanted a candidate with experience.

More than half the total delegates to the Democratic convention in August and about 40 per cent of the delegates to the Republican convention in September will be apportioned in Tuesday's voting.

Source : Agencies