An early morning deal struck by legislators from Prince George's County, Montgomery County and Baltimore City helped push the proposed new state lottery game, "Lotto," through the Maryland House of Delegates today by a vote of 86 to 44.

But the measure, designed to help financially strapped Prince George's County and Baltimore, may not bring in as much revenue this year as originally anticipated. Because it will take until November for the new game to start and because the game will not be in full operation until January, new estimates now show the game will only net about $18 million in fiscal 1984, rather than the $40 million estimated. From that figure, Prince George's and Baltimore will each get about $6 million, far less than the original $13 million each expected to receive.

That is the second piece of bad news for Prince George's, for another bill that would raise property tax increases on businesses in Prince George's and bring the county about $10 million, may be killed by a series of amendments offered by Del. Dennis C. McCoy (D-Baltimore).

"Last week, we thought we could come up with $23 million with these two bills," said Prince George's delegation chairman Charles J. Ryan. "Now, we may be down to $6 million."

Ryan was a key figure in the passage of Lotto today. Early this morning, at the request of Montgomery County delegation chairman Ida G. Ruben, a meeting was held in Ryan's office with Ruben, Montgomery Del. Mary Boergers, McCoy, Montgomery lobbyist Blair Lee IV and Prince George's Del. Gerard F. Devlin attending.

Ruben said she requested the meeting because of the hostility she was feeling from Prince George's and Baltimore after Monday's first vote on Lotto. Then, the bill came up one vote short of the needed 71, with only one of 19 Montgomery delegates voting for it.

"We don't want a schism here, we want to try to cooperate," Ruben said yesterday. "But the way the bill was written, with the local governments getting all the funds directly, we couldn't support it."

The money generated by Lotto would be returned to localities in proportion to each jurisdiction's overall lottery sales, including sales of Instant Lottery game tickets. In the past, all lottery money has gone directly into the state's general fund.

Today's vote was Lotto's last chance. A compromise was offered at the meeting in Ryan's office. McCoy and Devlin would publicly promise to support amendments to the bill added on in the Senate; in return, Ruben and Boergers would support the bill in the House and urge other members of their delegation to do the same.

One amendment would ensure that if Lotto cut into state money made from other lottery games, Lotto funds would be used to make up the difference. The other said the game would be terminated after two years.

The compromise was a major victory for Montgomery since Baltimore and Prince George's had maintained they would get the bill passed without the county's support.

In fact, on Monday after the first vote, one Baltimore delegate stormed past a female Montgomery delegate railing, "We don't need you broads anyway." Thirteen of the 19 Montgomery delegates are women.

After the meeting, McCoy did his best on the House floor to do everything but make a commitment to supporting the changes in the bill. Del. Theodore Levin (D-Baltimore County) then moved to refer the bill back to the House committee, a move that might have killed the bill.

Devlin then came to the rescue, saying he would personally testify on behalf of the amendments in the Senate. Eventually, the motion to send the bill back to committee was defeated and the full measure passed, 12 Montgomery delegates voting for the bill.

In Lotto, players would pay a fixed amount, perhaps 50 cents, to select six numbers in whatever sequence they wish. Winning numbers would be drawn weekly, hence the game's nickname as "the Saturday night special."

The odds against winning the grand prize by matching all six of the number in order are estimated to be 250,000 to 1, according to Devlin.