Chief Judge Merrick B. Garland of the United States Court of Appeals for the D.C. Circuit is seen in an undated handout picture. [Photo/Agencies]

WASHINGTON  - US President Barack Obama will nominate appellate court judge Merrick Garland to the Supreme Court on Wednesday, the White House confirmed, emphasizing his readiness for the job and history of support from Republicans and Democrats.

"No one is better suited to immediately serve on the Supreme Court," a White House official said.

"Chief Justice John Roberts, Garland's colleague on the D.C. Circuit, once said that 'anytime Judge Garland disagrees, you know you're in a difficult area,'" the official added.