Casper, Wyo. ? Sen. Barack Obama captured the Wyoming Democratic caucuses Saturday, seizing a bit of momentum in the close, hard-fought race with rival Sen. Hillary Clinton for the party’s presidential nomination.

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

Obama has also shown strength in the Mountain West, winning Idaho, Utah, Colorado and now Wyoming. The two split Nevada, with Clinton winning the popular vote and Obama more delegates.

But Clinton threw some effort into Wyoming, perhaps hoping for an upset that would yield few delegates but considerable buzz and momentum. The New York senator campaigned Friday in Cheyenne and Casper. Former President Clinton and their daughter, Chelsea, also campaigned this week in the sprawling and lightly populated state.

Obama campaigned in Casper and Laramie on Friday, but spent part of his time dealing with the fallout from an aide’s harsh words about Clinton and suggestions that Obama wouldn’t move as quickly 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 last Tuesday, 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.

Obama had 61 percent, or 5,378 votes, to Clinton’s 38 percent, or 3,312 votes, with all 23 Wyoming counties reporting.

Obama won seven delegates and Clinton won five. In the overall race for the nomination, Obama led 1,578-1,468, according to the latest tally by The Associated Press. It will take 2,025 delegates to win the Democratic nomination.

Obama campaign manager David Plouffe said the Wyoming victory speaks to the candidate’s strength in the West, and that Obama is better suited to help down-ticket Democrats even in states that traditionally vote Republican in the general election.

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