Sen. John C. Coolahan, a fiery Baltimore County Democrat who lent a voice of fiscal conservatism to the powerful Senate budget committee, resigned from that panel today, citing Senate President Melvin A. Steinberg's leadership style as the chief reason.

"Mickey doesn't want effective leadership -- he wants boot-lickers," said Coolahan, 52, a 14-year veteran of the General Assembly.

Coolahan said he was embittered by Steinberg's handling last week of an across-the-board cut in state personnel and an investigation of state police promotions, two proposals supported by Coolahan and other members of the Senate Budget and Taxation Committee.

At a meeting with Steinberg today, Coolahan said he expressed his dissatisfaction with the Senate president and demanded to be reassigned to another committee.

"I told him I don't give a damn which one," said Coolahan, adding that he expects to remain on the committee for the final 13 days of the 1985 General Assembly.

Steinberg could not be reached for comment tonight.

Coolahan said he objected most to Steinberg's handling of the 2 percent management cut twice approved by budget committee members on 8-to-5 votes. Steinberg lobbied hard against the management cut and made overturning it a "leadership" issue, meaning that committee chairmen, vice chairmen and others were expected to follow his lead and reject the cut.

The Senate killed the management cut on a 31-to-14 vote last week.

"It was raw power and it totally destroyed the committee," said Coolahan, who noted that in the full Senate vote budget committee chairman Laurence Levitan (D-Montgomery) and the vice chairman supported Steinberg instead of voting for the cut approved by their committee.

Coolahan said he was also angered by Steinberg's refusal to approve a proposed Senate investigation into the promotional practices of the State Police. Steinberg had endorsed such an investigation only two weeks ago, Coolahan said.

Today, however, Steinberg told reporters that he had ruled out such an inquiry for the time being.

"He's blocking an investigation that our committee supports," Coolahan said.

He added he was leaving the committee "with regret since while I've been there I've worked hard to keep spending down."

Levitan, for his part, said he would miss Coolahan if he leaves the committee, but added that he doubts Coolahan will. "I don't know that he's serious," Levitan said. "He's smart; he does a good job. He grabs hold of an issue but when he loses sometimes he sulks."