Democrat Barack Obama beat rival Hillary Clinton in Wyoming's nominating contest on Saturday, bouncing back from a string of losses that gave Ms. Clinton new life in their hotly contested presidential battle.

Mr. Obama's victory in the nominating caucus in sparsely populated Wyoming slowed Ms. Clinton's momentum after she won three of four contests on Tuesday in their tight duel for the right to face Republican John McCain in November's presidential election.

With 96 percent of caucus sites reporting, Mr. Obama led Ms. Clinton by 59 percent to 40 percent.

"This is a very important win for us," said David Plouffe, Mr. Obama's campaign manager, in a conference call with reporters. He noted that Ms. Clinton, her husband Bill Clinton and daughter Chelsea all campaigned in the state.

Heavily Republican Wyoming has just 12 delegates to the August convention that will pick the Democratic nominee, one of the smallest hauls in the race, but every state has become crucial in the prolonged battle between the two senators.

Both Mr. Obama and Ms. Clinton campaigned in Wyoming on Friday, but the two candidates took the day off at home on Saturday. Next up is a primary in Mississippi on Tuesday before Mr. Obama and Ms. Clinton square off in Pennsylvania on April 22.

The win allowed Mr. Obama to add slightly to his almost insurmountable lead in the pledged delegates who will help decide the nominee. The exact breakdown of delegates in Wyoming was not immediately clear.

Neither Mr. Obama nor Ms. Clinton is likely to reach the 2,025 delegates needed to clinch the nomination without help from 796 "superdelegates" - party officials and insiders free to back any candidate.

The states of Michigan and Florida, which were stripped of their delegates in a dispute with the national party and held unsanctioned contests, also could figure in a final resolution to the tight race.

Officials in both states have discussed redoing their contests so they would produce delegates to the convention, but the candidates, the state parties and national party would have to agree on the timing, funding and formats.

The Wyoming caucus requires voters to turn up at public sites at specific times. Democrats in heavily Republican Wyoming crowded the 23 caucus sites around the state.

Mr. Obama, an Illinois senator, has been particularly successful in caucuses, where his organizational strength and grass-roots enthusiasm have given him an advantage.

Ms. Clinton, a New York senator, has complained about the caucus system and said she performs better in primary elections in big states such as Ohio, California and New Jersey that Democrats will have to win to capture the White House.

"There is not a lot of opportunity for people to participate," Ms. Clinton said of caucuses in Wyoming on Friday.

Wyoming, the home state of Republican Vice President Dick Cheney, has not voted for a Democrat for president since 1964. It does have a popular Democratic governor, Dave Freudenthal, who has not endorsed either Mr. Obama or Ms. Clinton.