Trump tweeted that he has made his decision and that he will make the announcement at 8 p.m. Eastern Time.
The Supreme Court has been left with eight justices since February of last year after the death of Antonin Scalia. President Barack Obama put forward Merrick Garland to fill the vacancy, but the nomination was blocked by Republicans who wanted to delay filling the vacancy until after the election.
Federal appeals court judges William Pryor, Neil Gorsuch and Thomas Hardiman are front-runners to fill the seat, according to a person familiar with the process who was not authorized to speak publicly about internal decisions and discussed the search on condition of anonymity.
The Associated Press contributed to this report