In 1937, Seversky entered a P-35 (company designation NF-1, NF for Naval Fighter) in a US Navy competition for a new carrier-based fighter to replace the Grumman biplanes then in service. It competed against the Grumman F4F and the Brewster F2A. It was powered by a 950 hp Wright R-1820-22 engine, and carried an arrestor hook and bomb racks. Visibility was improved by the fitting of a larger bulged windscreen. The top speed was only 267 mph, not much faster than that of the Grumman F3Fs that was intending to replace. In any case, the Brewster F2A won the competition and the NF-1 was not developed any further.
Some sources have the plane being designated FN-1, but the plane never received a Navy designation, contract, or serial, but was known only by its factory designation of NF-1 and used only the civil registration NX1254.