Democrat Barack Obama tried to translate weekend victories into momentum going in this week's US presidential nominating contests but Republican John McCain's march hit a few bumps in the road.

Mr McCain, an Arizona senator who became the likely Republican nominee last week when his chief rival dropped out, lost two of three state contests on Saturday but got a vote of confidence from President George W. Bush yesterday.

Mr Obama, an Illinois senator who would be the first black President, scored decisive wins over New York Senator Hillary Clinton on Saturday in Louisiana, Nebraska and Washington in the race to be the Democratic nominee in the November 4 election.

Former Arkansas Governor Mike Huckabee beat Mr McCain in Louisiana and Kansas and ran a very close second in Washington state. Represetative Ron Paul of Texas, far behind in the Republican race, was a close third in Washington.

"It was great day for us," Mr Huckabee said yesterday on NBC's Meet the Press show. "This thing could go to the convention."

While saying he was staying in the race, Mr Huckabee added that if Mr McCain won the 1,191 delegates needed to capture the Republican nomination at the party's national convention in September, he would bow out.

Mr McCain has captured just less than two-thirds of that number of delegates with more than 20 of the 50 states still to hold Republican nominating races.

Mr Bush has refused to endorse a Republican candidate as long as Mr Huckabee is still in the race but came close on Friday when he told a conservative conference, without mentioning names, that the party would soon have a nominee and needed to unite behind him.

Mr Bush tried to calm fears among conservatives yesterday that Mr McCain was too liberal by calling him a "true conservative."

"If John's the nominee, he has got some convincing to do to convince people that he is a solid conservative," Mr Bush said on Fox News Sunday. "And I'll be glad to help him if he's the nominee, because he is a conservative."

Democrats held a nominating contest in Maine yesterday but the next big voting day comes tomorrow around the US capital. Both parties have contests in Washington, DC, and neighbouring states Virginia and Maryland.

Mr Obama was running ahead in opinion polls and was expected to do well in tomorrow's balloting. He tried to stress the breadth of his wins as he campaigned in the area.

"Today, the voters from the West Coast to the Gulf Coast to the heart of America stood up to say yes, we can," Mr Obama said at a party dinner in Richmond, Virginia, on Saturday.

"We won in Louisiana, we won in Nebraska, we won in Washington state, we won North, we won South, we won in between, and I believe that we can win Virginia on Tuesday if you're ready to stand for change."

Mrs Clinton, who would be the first woman President, and Mr Obama are about even in pledged delegates but both are well short of the 2,025 needed to win the Democratic nomination.

The wins by Mr Huckabee, a folksy Baptist preacher, came in states with big Christian conservative voting blocs and did not change Mr McCain's daunting advantage in the Republican contest.