Barack Obama defeated Democratic rival Hillary Clinton in Saturday's Wyoming caucuses, according to U.S. media, in the latest battle in the tight race for the party's presidential nomination.

Democratic presidential hopeful Barack Obama smiles as he walks around on stage during a campaign rally Friday in Laramie, Wyo.
(Laramie Boomerang/Andy Carpenean/Associated Press)

Hoping to regain momentum after key losses to Clinton in Texas and Ohio last Tuesday, Obama secured 61 per cent to Clinton's 38 per cent, CNN and CBS reported, with all 23 precincts counted.

CNN said Obama won seven delegates and Clinton won four, with one delegate still outstanding in the proportional vote.

Obama's campaign, once surging, appeared to slow entering the Texas and Ohio contests amid a renewed attack of his credentials by the Clinton campaign, as well as a media storm surrounding a leak of diplomatic information from Canada that drew questions over the sincerity of Obama's anti-NAFTA stance.  

Ahead of the Wyoming contest, the Illinois senator held the lead in delegates, 1,571-1,463, according to an Associated Press tally. But Clinton held the edge with superdelegates — senior party officials and elected leaders — 242-210. A total of 2,025 delegates are needed to win the nomination.

Obama generally has outperformed Clinton in caucuses, which reward organization and voter passion more than do primaries. Obama has now won 13 caucuses to Clinton's three.

Obama spent part of his time in Wyoming dealing with the fallout from an aide calling Clinton "a monster" and suggestions that Obama won't move as quickly as he says he will to withdraw U.S. forces from Iraq if elected.

In Casper, Obama said Clinton had no standing to challenge his position on the war because she had voted to authorize it in 2002.

Clinton, buoyed by big wins in Ohio and Texas, said she faced an uphill fight in Wyoming. Her campaign also holds out little hope for Tuesday's primary in Mississippi, which has a large black population.

Both candidates were looking ahead to the bigger prize — delegate-rich Pennsylvania on April 22.

In Wyoming, 12 national convention delegates were at stake. During the first caucuses of the day, it appeared the state's Democrats were showing up in record numbers. In 2004, a mere 675 people statewide took part in the caucuses.

The party will officially name a candidate at their national convention in Denver in August.

With files from the Associated Press