Senate Republicans on Wednesday failed for a fourth time to break a Democratic filibuster thwarting a vote on President Bush's nomination of Miguel Estrada for a federal appeals court.

Republicans need 60 votes to end the filibuster and then a majority to approve Estrada for a seat on the U.S. Court of Appeals for the District of Columbia Circuit. Their latest effort again fell short, this time by a 55-44 vote.

Republicans hold a 51-48 edge in the Senate, with one independent.

Estrada, who was first nominated almost two years ago, is a 41-year-old Honduran immigrant who graduated from Harvard Law School, served in the Justice Department during the Clinton administration and practices law in Washington.

Democrats, who want more information about Estrada, have asked him to answer more questions and have urged the White House to release memos Estrada wrote while working for the Justice Department.

The Bush administration has refused to release those memos. Republicans have accused Democrats of treating Estrada unfairly because he is a conservative Hispanic.

Every Republican voted to end the filibuster. They were joined by Democratic Sens. Bill Nelson of Florida, Ben Nelson of Nebraska, John Breaux of Louisiana and Zell Miller of Georgia.

The rest of the Democrats and independent Sen. Jim Jeffords of Vermont voted against ending the filibuster. Sen. John Kerry, D-Mass., was not present for the vote.