Maryland Senate President Melvin Steinberg, Baltimore Mayor William Donald Schaefer's running mate in the race for the Democratic gubernatorial nomination, has accepted an invitation to debate the No. 2 man on the ticket of Attorney General Stephen H. Sachs.

But the Sachs campaign, in a political tit for tat, said Sachs' running mate, Rep. Parren Mitchell, would not debate Steinberg unless the mayor changed his mind and agreed to a series of debates with Sachs.

Schaefer has appeared with Sachs at two forums, and he also attended one hour of a two-hour radio debate after having announced earlier that he would not participate. The Sachs' campaign said none of the joint appearances constituted a full-fledged debate.

Schaefer "kind of puts his foot in the pool and then runs away," said Blair Lee IV, Sachs' campaign manager. "We're trying to create some kind of incentive for Schaefer to really debate."

Steinberg told a news conference that he is eager to face Mitchell in a two-hour lieutenant governor's debate Aug. 14 sponsored by the League of Women Voters and WBAL radio. "I don't believe it is fair for the Maryland public not to hear from the candidates for lieutenant governor," he said.

While Steinberg said a debate would provide a good forum for the two candidates, Schaefer has said he does not believe debates are worthwhile.

But the public is anxious to see the two leading candidates for governor square off, Lee contends. "Clearly people are interested in what these guys are made of and how they react under pressure," Lee said. Democrats Pool Resources

In a show of solidarity designed to pool resources, 57 diverse Montgomery County Democrats have formed a ticket to boost their candidacies in the primary and general elections this fall.

By coming together under the banner of "Dems for '86," the candidates for the General Assembly, County Council, courthouse offices, and Democratic Central Committee will be able to pool thousands of dollars to fund the mailing of campaign literature to prime voters.

Missing from the ticket are candidates for county executive and for state senator from legislative District 19. That's because three Democrats are battling to become the next executive, while two party stalwarts, Dels. Idamae Garrott and Lucille Maurer, are vying for the Senate post. Report: Candidate Asked to Quit

The Baltimore Sun reported this week that Baltimore County Del. Dale Anderson, acting with what he said was the knowledge of Baltimore Mayor William Donald Schaefer, suggested to a candidate for county executive that he could have a state job if he withdrew.

Council Council member John W. O'Rourke told the Sun that Anderson, a former county executive, made the offer to him July 9, the day before the deadline for withdrawing, and said he had discussed it with Schaefer. Anderson confirmed that the meeting had occurred, the paper said.

If O'Rourke had withdrawn, the Sun said, it could have benefited one of his Democratic primary opponents, state Sen. Dennis F. Rasmussen. Rasmussen is a close ally of Schaefer's running mate, Senate President Melvin A. Steinberg.