PLAINVILLE - Any chance of Plainridge Racecourse and the state's other three racetracks operating slot machines will likely have to wait until next year.

A last-minute pitch to get a revised slot machine proposal before the Legislature before it ends its session the end of July appears dead, supporters say.

The bill, which called for each track to have 2,000 slot machines, appears to have fizzled in a disagreement over which legislative committee should take it up. The Senate wants the Consumer Protection Committee to tackle the proposal while the House sent it to the Committee on Emerging Technologies and Economic Development.

Bringing slot machines to the tracks would have generated about $500 million a year for the cash-strapped state and cities and towns, backers say.

While the bill was considered a longshot, state Rep. Richard Ross, R-Wrentham, whose district includes Plainville, and other slot machine supporters were hoping to at least see debate on it. "We thought it had a chance," Ross said Friday.

House Speaker Sal DiMasi, who had previously promised to bring the issue to the floor, said the bill was "in limbo" because of the committee debate.

Supporters are blaming Senate President Therese Murray, however, for the latest roadblock. A spokesman for Murray strongly denied that.

"It looks like Senate President Therese Murray refuses to place it before a committee," Ross said. "Without going to committee, it looks like it won't get voted on this session. That is an extreme disappointment."

The legislator added "some committee chairs are not very receptive" to a slot machine proposal either.

Ross and others pledge to work to ensure the issue resurfaces when the Legislature reconvenes in January.

"I heard the governor is becoming a little more sensitive to the fact this would be the quickest way to get revenue flowing," Ross said. Casinos that Gov. Deval Patrick has been advocating would take several years to get up and running while track operators such as Plainridge's Gary Piontkowski say they could be operating slot machines within three months.

"We just need to make sure our town government people are involved and recognize the amount of money being left on the table. Hundreds of millions of dollars are certainly worth fighting for," Ross said. "Hopefully our colleagues will hear the message loud and clear and realize they are missing a great opportunity here. We are looking at a half million dollars or better for most communities in this area."

Ross noted Sen. Scott Brown, R-Wrentham, has been working up support on the Senate side for slot machines. "We are both on the same page on this," Ross said.

Also this week, Piontkowski and Richard Dalton, president of Wonderland Greyhound Park, sent a letter to legislators and the mayors and boards of selectmen in Massachusetts' 351 cities and towns, highlighting how much would have been distributed to municipalities if slot machines had been approved two years ago.