The Senate approved the nomination of former senator James L. Buckley (R-N.Y.) to the U.S. Court of Appeals here yesterday, the 19th judge confirmed in two days after a partisan feud was resolved.

The logjam was broken by a political deal in which Senate Republicans agreed to allow the Democrats more time to investigate the backgrounds of future judicial nominees. As part of the agreement, the Senate Monday confirmed CIA general counsel Stanley Sporkin, whose nomination had been held up for 17 months, for a seat on U.S. District Court here.

Also joining the federal district court here is George H. Revercomb, who has been a D.C. Superior Court judge for 15 years. He was confirmed Monday.

The confirmations bring the total of President Reagan's appointments to the federal bench to 251 -- more than a third of the 743 total. Reagan's effort to appoint conservatives who share his judicial philosophy has turned many of these nominations into ideological battlegrounds, with liberals charging that the president is picking too many unqualified or extremist candidates.

Democrats also contended that the Senate Judiciary Committee's GOP majority was rushing through conservative nominees while stalling on Sporkin, who drew conservative ire during his aggressive tenure as enforcement chief of the Securities and Exchange Commission in the 1970s.

The nomination was held up while Sen. Jeremiah A. Denton (R-Ala.) held five closed hearings on allegations that Sporkin improperly intervened in an investigation of a Central Intelligence Agency leak, which Sporkin denied.

To ensure that Sporkin's name reached the Senate floor before the Christmas recess, Democrats blocked a dozen other judicial nominees, including Deanell Tasca of Kansas, who is from the home state of Majority Leader Robert J. Dole. As a further protest, they briefly held up the nomination of Health and Human Services Secretary Margaret M. Heckler to be ambassador to Ireland.

Dole and Minority Leader Robert C. Byrd (D-W.Va.) eventually negotiated a truce that allows the Democrats unlimited time to investigate Reagan's most controversial judicial nominees.

Buckley's path to the bench illustrates the political maneuvering that often accompanies such nominations.

A former Conservative Party stalwart in New York and onetime head of Radio Free Europe/Radio Liberty, Buckley was originally considered for the 2nd Circuit Court of Appeals, which covers New York, Connecticut and Vermont.

But opposition from liberal Connecticut senators Lowell P. Weicker Jr. (R) and Christopher J. Dodd (D) persuaded the administration to place Buckley on the D.C. appeals court, where no home-state senators could block him.

Still, Buckley's nomination was delayed when the District of Columbia Bar complained that no Washington attorneys had been consulted. The New York City Bar Association also opposed Buckley because the former senator refused to meet with the group. And Weicker and Dodd protested Buckley's lack of legal experience and strongly held conservative views.

Despite the criticism, the Senate confirmed Buckley 84 to 11. Reagan plans to nominate another controversial conservative, Office of Management and Budget general counsel Michael J. Horowitz, to the influential appeals court here.

The Senate also confirmed New York lawyer Arthur I. Burns as associate attorney general, the third-ranking Justice Department post, for which William Bradford Reynolds, head of the Civil Rights Division, was turned down in June.