Maryland received bids Friday to operate casinos at the two locations — in downtown Baltimore and western Maryland — that had proved tough sells since the state launched its slot-machine gambling program nearly three years ago.

The interested parties, which include a group affiliated with Caesars Entertainment, will be required to undergo background checks in coming months and are not guaranteed licenses.

Still, Friday’s results raised the odds considerably that the state’s gambling program, which has had multiple setbacks, could have a full complement of operators by next year.

“The encouraging thing is it does give us applicants for all five sites,” Donald C. Fry, chairman of the commission that picks the state’s slots operators, said at a news briefing where very basic details of the proposals were released.

Two groups submitted bids for the site in Baltimore, where the state has authorized a casino with up to 3,750 machines, second in size only to one now being built at an outlet mall in Anne Arundel County. The Baltimore location is just south of M&T Bank Stadium, where the Baltimore Ravens play.

Only one of the two bidders, the group affiliated with Caesars, submitted a required $22.5 million initial license fee. More than two dozen people are listed as principals in the group. Fry indicated that the other bidder would likely be disqualified.

Three applicants put in bids for a smaller casino at the Rocky Gap Lodge and Golf Resort in Allegany County, where up to 1,000 slot machines are allowed. Proposals for the site, a state-financed resort that continues to struggle to turn a profit, ranged from 200 to 850 machines.

Bidders for Rocky Gap include Nathan Landow, a developer from Montgomery County and former chairman of the Maryland Democratic Party. The other two groups listed multiple principals.

Two of Maryland’s five casinos are now open: Hollywood Casino Perryville, a stand-alone 1,500-machine facility in Cecil County; and the Casino at Ocean Downs, an 800-machine facility adjacent to a horse track in Worcester County.

The operator of Maryland Live!, which is rapidly rising out of a parking lot at Arundel Mills mall, says it will open its doors in June. The Washington Post reported this week that the developer, Baltimore-based Cordish, is seeking some of its financing from wealthy Chinese investors.

Luring operators for the Baltimore and Rocky Gap locations has been challenging for the state, in part because of the limited capital available for such projects in recent years.

In an initial round of bidding conducted in early 2009, the state drew one applicant to build and operate the Baltimore site. Later that year, Fry’s panel rejected the applicant, Baltimore City Entertainment Group, amid questions about whether it could afford to finance the project.

The group has since filed two lawsuits, one directly related to the panel’s decision and the other alleging that the process amounts to reverse discrimination because of minority-participation goals, which have since been altered.

Fry had said the group could have submitted a new bid that would be considered “without prejudice.” Instead, it announced Thursday that it would continue to pursue legal remedies and accused the state panel of “mismanagement.”

Fry’s panel initiated a third round of bidding for the Rocky Gap site in June after the legislature took several steps earlier this year to sweeten the offer, including temporarily increasing the share of proceeds for an operator. A portion of the initial license fee was also waived for the site.