A U.S. magistrate in Alexandria ruled yesterday that the government had presented sufficient evidence to have a grand jury consider a case involving William A. Borders Jr., a prominent Washington lawyer accused of being a conduit for a $150,000 bribe to a Miami federal judge.

Magistrate W. Harris Grimsley acted after an FBI agent testified that Borders told an undercover agent that he was serving as the middleman in an alleged payoff scheme on behalf of U.S. District Judge Alcee L. Hastings, 45, of Miami.

Hastings has not been charged. But he has said that he is a target of the probe of allegations that a $150,000 payment was made in an effort to get sentence reductions for two brothers who were sentenced by Hastings .

FBI agent William J. Murphy testified at yesterday's preliminary hearing that Borders accepted $25,000 from an undercover agent posing as one of the brothers in Miami Sept. 19.

When Borders was arrested in Arlington Oct. 9, Murphy testified, the undercover agent had placed an additional $125,000 on the front seat of Borders' car, between the agent and Borders.

Borders, 42, is a member of the D.C. commission that recommends selection of city judges. He remains free on $25,000 bond.