DioGuardi represented suburbs north of New York City for two terms before he was defeated by Democrat Nita Lowey in 1988.
His campaign said Friday he will make an official announcement on Tuesday at Grand Central Terminal in Manhattan.
DioGuardi has a reputation as a kinetic politician and a fiscal conservative. He would join a Republican field that already includes former Nassau County lawmaker Bruce Blakeman. A number of other Republicans are considering a run.
The Post said Taylor, the longtime girlfriend of Mayor Michael Bloomberg, had been approached privately by some Washington-based Republicans "to gauge whether she had an interest" in seeking the seat. - AP