WASHINGTON — President Bush named Republican fund-raiser Sam Fox as the American ambassador to Belgium yesterday, using a maneuver that allowed him to bypass Congress where Democrats had derailed Mr. Fox’s nomination.

Democrats had denounced Mr. Fox for his 2004 donation to the Swift Boat Veterans for Truth. The group’s TV ads, which claimed that Senator Kerry exaggerated his military record in Vietnam, were viewed as a major factor in the Massachusetts Democrat losing the election.

Recognizing Mr. Fox did not have the votes to obtain Senate confirmation, Mr. Bush withdrew the nomination last month. Yesterday, with Congress out of town for a spring break, the president used his power to make recess appointments to put Mr. Fox in the job without Senate confirmation.

This means Mr. Fox can remain ambassador until the end of the next session of Congress, effectively through the end of the Bush presidency.

Mr. Bush also used his recess appointment authority to make Andrew Biggs deputy director of Social Security.

The president’s earlier nomination of Mr. Biggs, an outspoken advocate of partially privatizing the government’s retirement program, was rejected by Senate Democrats in February.

Mr. Fox, a 77-year-old St. Louis businessman, gave $50,000 to the Swift Boat group.