Sen. Harry F. Byrd Jr. (I-Va.) moved closer yesterday to a showdown with the Carter administration over the nomination of new four federal judges in Virginia.

Byrd, in a speech before the Virginia Realtors Association in Richmond, said he will oppose the nomination of anyone other than the 10 white male candidates he has suggested for the four newly created federal judgeships in the state.

The president has nominated two candidates from Byrd's list, and is believed to be ready to pick a third, but he also reportedly will nominate a black circuit court judge from Richmond for the fourth spot.

The White House has been pressuring Byrd to expand his list of candidates to include blacks and women, to help Carter fulfill a campaign promise to appoint more women and minorities to the federal bench. But Byrd has refused, saying he followed the established practice of forwarding names of candidates selected by two commissions he formed two years ago.

A senator traditionally is able to block presidential appointments in his home state by refusing to pass on to the Judiciary Committee the "blue slips" which bear the nominee's name.

Byrd told the real estate brokers yesterday that he is "in a bit of a controversy with the president" over the nominations. "It's never pleasant to have a confrontation with the president of the United States," he added, but if Carter nominates someone not on his list, Byrd said "that would force a confrontation."

The Justice Department is believed to be conducting a background check on Circuit Judge James Edward Sheffield, a black, and State Sen. J. Harry Michael Jr. (D-Charlottesville) for the two judgeships that remain available. The president previously nominated two others from Byrd's list, but their confirmation has been delayed pending the resolution of the dispute between the senator and the White House on the other two nominees.