Four casino operators are pursuing bids in Springfield, which has become the hottest destination in the state for the gambling industry.

Specialists on the casino industry said the mayor’s willingness to allow more than one proposal to move forward could increase the city’s chances of hosting the sole gambling resort allowed by law in the state’s western region.

“I have instructed our city departments and our consultants to conduct an open, fair, and robust competitive process that will allow me to choose that project or projects that best meet the city’s selection criteria,” Sarno said in a statement, which also outlined the city’s process for evaluating casino proposals.

The mayor said he expects the developers to provide detailed information and make public presentations about their proposals on an aggressive timetable over the next several months. Sarno would then choose one or more enterprises to negotiate the terms under which Springfield would agree to host a casino, the statement said. Those negotiated agreements would need approval by the City Council and then by local voters in a referendum.

The state gambling commission will ultimately choose which projects receive coveted state licenses. The panel controls three resort licenses; one is designated for Western Massachusetts. In addition to the Springfield proposals, the operators of the Mohegan Sun casino in Connecticut are pursuing the western license with a project proposed in Palmer.

Sarno originally told the Globe in July that he intended to negotiate with only one casino operator. In response, one of the companies pursuing a bid in Springfield — Ameristar, which is proposing a resort on 41 acres the company owns several miles from downtown — raised concerns that Springfield would hurt its chances to host any resort at all if the city insisted on eliminating as many as three proposals.

Troy Stremming, an Ameristar senior vice president, said Monday that the company was pleased with Sarno’s announcement. “It makes sense to us to give Springfield the most opportunities possible to land this casino,” he said.

MGM Resorts joined the Springfield casino sweepstakes last week, unveiling plans for an $800 million gambling and entertainment complex on a three-block site in the South End that was damaged by a 2011 tornado.

Penn National Gaming recently confirmed that it plans to build a resort on a site that includes the current Peter Pan bus terminal, the offices of The Republican newspaper, and some nearby riverfront land.

“We’re committed to this market,” said Penn National spokesman Eric Schippers.

Hard Rock International has also shown interest in building a casino in Springfield.

Casino operator representatives each met privately with Sarno Monday to hear the city’s evaluation process.