Judge Merrick B. Garland

WASHINGTON — President Barack Obama will nominate federal appeals court judge Merrick Garland to the Supreme Court, congressional sources said today. The pick sets up a confrontation with Republicans who say they will refuse to consider his nomination in an election year.

Garland, 63, is the chief judge for the United States Court of Appeals for the District of Columbia Circuit, a court whose influence over federal policy and national security matters has made it a proving ground for potential Supreme Court justices.

He would replace conservative, Justice Antonin Scalia, who died unexpectedly last month, leaving behind a bitter election-year fight over the future of the court.