The sides had reached an impasse after their last talks in late June, thought to be over language that would allow the union to organize workers at future Strip locations where MGM Mirage maintains a partnership.

The casino operator previously had agreed to let the union organize workers at CityCenter, the company's $7.4 billion Strip development project expected to open in 2009. CityCenter will include an MGM Mirage-operated 4,000-room hotel-casino and smaller boutique hotels and other entertainment offerings operated under a joint venture.

Since contract talks began, MGM Mirage had entered into several other joint venture development plans, including a deal with Kerzner International Holdings to develop a project on 40 acres at the north end of the Strip across from the Sahara.

Culinary union political director Pilar Weiss said Wednesday that labor leaders were "ecstatic" over the joint venture language reached in the tentative agreement.

"They called us this morning and asked us to meet today," Weiss said. "They've had our proposal for a while. In reality, we really weren't that far apart. Obviously, we're happy with today's events."

With Harrah's settled and MGM Mirage on the verge of a settlement, the Culinary will have locked up new contracts covering the majority of the 50,000 hotel, casino and restaurant employees whose contracts expired May 31.

The union continues negotiations with smaller Strip and downtown casinos. Approximately 11,000 members of the Culinary union continue working under extensions while they negotiate new contracts on the Strip and downtown.

MGM Mirage spokesman Alan Feldman declined to comment on the agreement and said the company would discuss the matter after MGM Mirage workers vote on Friday whether or not to ratify the agreement.

Representatives of MGM Mirage and a committee of hundreds of rank-and-file members of the Culinary, with Bartenders Local 165, negotiated the agreement.

Weiss would not discuss particulars of the contract but said it was similar to the agreement the company reached in June with Harrah's Entertainment. That agreement covers six Strip casinos and approximately 15,000 workers.

The Harrah's contract calls for annual raises and increases to the employee benefits package.

The union reached a new contract with the Riviera covering about 1,000 workers. It was ratified Tuesday.

"Obviously, with MGM, they are much farther along with their joint ventures than any other companies," Weiss said.

The union has a separate 10-year agreement with Wynn Las Vegas, which was signed in 2005.

In July, the Culinary announced it was scheduling a strike authorization vote on Sept. 12 in which workers at hotel-casinos without new contracts can vote to give their negotiating committees the OK to call a strike.

The move does not mean a strike is imminent, only that the negotiating teams would have the power to call for a work stoppage.

Culinary Secretary-Treasurer D. Taylor had called in February for early talks because of the number of properties with soon-to-be-expired contracts.

In a statement late Wednesday, Taylor thanked the union's negotiating committee and MGM Mirage officials.

"The committee and the company worked hard over the last five months to make sure that this new contract maintains and strengthens the standards that have been set in Las Vegas for gaming employees," Taylor said.

The union hall became a key location for Democratic presidential candidates to address members of the union, which is seen as a key player in Nevada's early presidential caucus.

Culinary members have been visited on several occasions by top-tier candidates, several of whom vowed to walk a picket line if a strike occurred.

Within two hours of the announcement of the tentative agreement Wednesday, Democratic presidential candidate John Edwards, who was in Nevada on Wednesday, issued a statement lauding the pact.