Prince George's School Superintendent John A. Murphy has withdrawn his nomination for the top post in the Boston school system, saying school officials there are "more concerned with racial politics than educating children."

The Boston job search has been fraught with confusion and racial tension since the five semifinalists were announced on Nov. 21. A Hispanic superintendent of the Chelsea, Mass., schools threatened to sue Boston officials because the pool of semifinalists did not include either a Hispanic person or a woman. School officials reported that the semifinalists consisted of two black candidates, two whites and an Asian, prompting criticism that the pool did not reflect the diversity of a system where 80 percent of the students are minorities.

But on Tuesday, almost a week after the semifinalists were named, a Boston television station reported that one of the two nominees that school officials had identified as a black man was actually white.

"It got to the point that it was a circus," Murphy said yesterday. "They had quite a fiasco going on for about seven days about the same old business of a lot of racial and ethnic politics. I didn't want to get bogged down in that again."

Murphy has earned a national reputation for implementing a wide-ranging magnet school program and improving student test scores. But he has drawn criticism closer to home, particularly from Prince George's black residents who say Murphy has not done enough to raise minority student achievement.

Murphy's withdrawal from the Boston search marks the fourth time the superintendent's name has surfaced as finalist in a national job search only to see him pull out of the contest or lose the position to another candidate.

The superintendent's well publicized job saga began last spring when he withdrew his nomination for the top school post in Miami after Prince George's school officials offered him a 10-year contract and a $45,000 raise. He later canceled the agreement after it created an uproar over its cost.

Murphy later applied for the top New Jersey education job, withdrew and pledged to stay in Prince George's. He was later named one of three finalists for the Kentucky commissioner of education post, but was passed over.

Murphy said he will continue to look for another job but vowed not to let his job search interfere with his present duties.