NEW York Post radio reporter John Mainelli is the new program director at WOR (710 AM).

Mainelli, who has reported on radio for The Post since 1998, officially joins WOR tomorrow.

Mainelli was program director at WABC (770 AM) from 1988 to 1995, where he launched a lineup including Rush Limbaugh and Ed Koch.

He will no longer report for The Post, but will continue a monthly column for Talkers magazine.

This has been a big week for WOR, which announced last Thursday that Fox News Channel star Bill O’Reilly will begin hosting “The Radio Factor with Bill O’Reilly” weekdays at 3 p.m. beginning May 8.