President Barack Obama is likely to announce either Judge Sri Srinivasan or Judge Merrick Garland as his pick for U.S. Supreme Court nominee and the announcement could come as early as Wednesday, a source familiar with the selection process said Tuesday.

The team of advisers helping to vet candidates, line up their public supporters and answer the president's questions had finished its work as of Tuesday, the source said.

Obama is searching for a replacement for long-serving conservative Justice Antonin Scalia, who died on Feb. 13. Senate Republicans have vowed not to hold confirmation hearings or an up-or-down vote on any nominee picked by the Democratic president for the lifetime position on the court.