ALBANY — A brash state senator from Queens who was a central figure in the coup that led to a brief Republican majority in the Senate was found guilty Thursday on a misdemeanor charge for cutting his girlfriend’s face with a broken glass.

But Sen. Hiram Monserrate, 42, escaped conviction on a felony assault charge that would have led to his immediate expulsion from the Senate. That would have created a new round of intrigue in the always-combative Senate because Democrats, for possibly several months, would have been one vote short to adopt bills without the help of reluctant Republicans.

But his troubles are not over, and there was word in Albany that there could still be an effort to expel the freshman lawmaker— though it would have to be at a time when the Democrats, who hold a razor-thin majority, would not have an immediate need for his vote.

Monserrate was accused by prosecutors of slashing his girlfriend’s face with a broken glass last December after a loud quarrel. The freshman senator, a former New York City police officer, denied any wrongdoing, insisting that it was an accident.

In the nonjury trial, State Supreme Court Justice William

M. Erlbaum acquitted the lawmaker of felony assault in the face-slashing. But Monserrate still faces an uncertain future. He will be sentenced Dec. 4 on the misdemeanor conviction for the injuries he caused his girlfriend while dragging her from the Queens apartment where the quarrel began after he found a man’s business card in the woman’s purse.

The misdemeanor conviction could carry up to a year in prison. A year’s sentence would keep Monserrate from being able to vote in the Senate and would put pressure on Democrats to get him out of office.

Senate Democratic Conference Leader John L. Sampson of Brooklyn said Democrats “are discussing the potential for further action by the Senate.” He said the lawmakers will “review past practices” and “follow the letter of the law.” He did not elaborate whether that means Monserrate could face just a censure from his colleagues or something more serious such as expulsion, which would require 32 voters in a chamber with 32 Democrats, including Monserrate, and 30 Republicans.

The woman involved in the Dec. 19 incident, Karla Giraldo, told hospital workers who treated her that Monserrate had cut her face open during a fight. She later changed her story to side with Monserrate and say that it was an accident. The senator decided not to seek a jury trial.

“A terrible accident occurred to my girlfriend, Karla Giraldo, a person that I love, and I have to live with that forever. There were no winners here,” Monserrate told reporters in Queens after the verdict.

After the face cutting-incident, which occurred a month after he was elected to the Senate last year, Monserrate again gained unwelcome public attention when he was involved, briefly, in the June coup that led to the Republicans taking back control of the Senate.

But he rejoined his Democratic colleagues, which then led to a monthlong, 31-31 stalemate between the Republicans and Democrats in the 62-member chamber. The other Democrat who crossed the aisle in the coup, Sen. Pedro Espada Jr. of the Bronx, then flipped back to the Democrats after he was given the title of majority leader.