County conventions are the second step toward divvying up Nevada's 25 pledged delegates to the National Democratic Convention between Clinton and Obama.
In past years, the county convention meetings have been little more than rallies for the party's likely nominee. But with the presidential race so closely divided, campaigns encouraged large numbers of supporters to attend as part of a strategy to defend the delegates won at Jan. 19 precinct caucuses.
Rowdy crowds quickly filled the Las Vegas ballroom to capacity and forced casino staff to close the doors early, leaving hundreds of delegates outside, party leaders said.
"Unfortunately, all those who are eligible ... there is no physical way in this room to allow those delegates in," convention chairman Bill Stanley told the crowd as he asked them to agree to close the convention and hold the presidential vote at a later date.
The crowd initially greeted the notion with a chorus of "boos," but eventually was persuaded after entreaties from both campaigns.
No date for the new vote was set immediately. Clark County delegates account for 72 percent of the state convention delegation. State delegates will meet in May in Reno.
The confusion left the results of any Saturday voting vulnerable to a court challenge. Both campaigns told the state party they likely would raise the issue in court if the vote wasn't redone, according to a state party official who was not authorized to discuss the negotiations.
Vassiliadis said the Democratic National Committee has threatened to reduce Nevada's delegation to the national convention if the matter is not resolved.
Saturday's cries of disenfranchisement echoed those heard after the January precinct caucuses, in which Clinton won more precinct delegates but left Obama poised to pick up one more national delegate.
The Obama campaign complained that many of its supporters were shut out of those precinct meetings last month after the Clinton campaign distributed bad information about the caucus process.
The Nevada Democratic Party has appointed a committee to review the entire caucus process.
Both candidates had hoped to use the Saturday meetings court new support. Under party rules, delegates can switch alliances at each stage in the process. Nearly 440 delegates assigned to former candidates John Edwards and Dennis Kucinich were up for grabs statewide.
Early results from rural counties that were able to vote Saturday showed no major shifts in support for either candidate. Washoe County, home to the Reno-Sparks area, had not yet reported results.
