Nevada Gov. Brian Sandoval on Friday said he will announce an appointment to replace Sen. John Ensign, R-NV ahead of the senator's resignation date of May 3.

Ensign - facing the possibility of public hearings and legal proceedings stemming from an affair made public in 2009 and ramifications leading to alleged conflict-of-interest violations by a former aide - said late Thursday he would resign. 

The person Sandoval will name to replace Ensign, must be approved by the Senate and will hold the office until the next general election.

I take very seriously the importance of this appointment, so to speculate on potential candidates or appointment before then would be premature, Sandoval said in a statement.

In Nevada's history, only eight U.S. Senators have been appointed. The most recent was Paul Laxalt on December 18, 1974, according to Sandoval's office.

While two government investigations by the Justice Department and Federal Electoral Commission have found no violations, Ensign still faced an ethics investigation by a Senate panel. He may have also been subjected to further questioning after a former aide he dealt with - who took a job as a lobbyist - was indicted in March of conflict of interest charges. The former aide is the husband of the woman with whom he had an affair.