The commissioners who run the agency supplying water and sewers to Prince George's and Montgomery counties voted 4 to 2 yesterday to rehire Robert S. McGarry as the agency's general manager.

McGarry had earlier threatened to quit his job at the Washington Suburban Sanitary Commission because of political fighting that had stalled almost all major issues before the agency, including his contract.

When McGarry's contract came up two weeks ago, the Prince George's government and its three commissioners had wanted to delay any rehiring decision until they could discuss his role at the agency and whether he had shown any bias in favor of Montgomery.

The Montgomery government and its three appointed commissioners supported McGarry.

The conflict before the two counties was resolved earlier this week when the Prince George's Council wrote McGarry a letter stating its confidence in him and its support for a new contract.

The two commission votes against rehiring McGarry came from Prince George's Commissioner Lawrence Brooks, who was appointed by County Executive Lawrence Hogan, who was opposed to rehiring McGarry, and Prince George's Commisssioner Johanna Norris, who said she voted against a new contract because she wanted more time to discuss McGarry's role at the agency.