The administration of Mayor Domenic Sarno in Springfield will slow its local casino ­selection process, yielding to warnings from the state gambling commission that the city is moving too fast and runs the risk of choosing an unqualified developer.

The city agreed Tuesday to put off any local referendums on casino proposals until after the Massachusetts Gaming Commission completes a ­detailed investigation of each applicant’s finances and the background of key executives and employees, the city said in a letter to Stephen Crosby, chairman of the commission.

The delay could set back Springfield’s selection process by several months.

At least four gambling companies have expressed interest in building in Springfield: MGM Resorts, Ameristar, Penn National Gaming, and Hard Rock International.

Sarno’s administration had originally outlined a speedy competition to whittle down the applicants to one or two by December. Sarno planned to then negotiate agreements for Springfield to host a gambling resort with those companies. The negotiated agreement, or multiple agreements, would then go to voters for endorsement in a referendum planned for the spring, under the city’s original timetable.

But in a public meeting with Sarno and his staff last week in Springfield, the gambling commission warned that the city was moving too aggressively. Commissioners raised the concern that the city’s chosen ­developer could later be banned from bidding. The commission intends to vet all potential bidders, probably beginning late this year, and is not ­expected to finish its investigations until at least next spring. The commission has the author­ity to disqualify developers with shaky finances or with people of questionable character in key positions.

Commissioners also warned that they do not expect to finish writing the criteria by which they will judge competing projects until well into 2013. By choosing a winner too quickly, Springfield would have risked picking a project that could not meet the commission’s standards, the commission said.

Kevin Kennedy, chief development officer for Springfield, said the city will announce a new schedule for its selection process later this week.

The administration still strongly believes that the city will benefit from hosting a competitive process that forces the developers to compete for the opportunity to negotiate with Sarno, Kennedy said in an inter­view. But he said the admin­istration has recognized “the importance to the Gaming Commission of the financial stability and viability of who­m­ever we choose.”

Crosby told commissioners in a public meeting Tuesday that the public talks with Springfield will signal to other communities not to hold votes on casino projects until the commission has finished its inves­tigation of the applicants.

The commission was still waiting Tuesday for an Ethics Commission review of a possible conflict of interest on the part of Springfield’s casino consultant, Shefsky & Froelich. The Chicago law firm is the registered lobbyist in Illinois for MGM and Penn National, two of the firms expected to compete in Springfield. An opinion from the Ethics Commission is expected soon. Shefsky & ­Froelich has promised to ­make the opinion public.