CRJ-700 Captain reported on takeoff roll receiving a steering inop caution message resulting in the flight crew rejecting the takeoff and returning to the gate.

Narrative

During the takeoff roll on Runway XX; a STEERING INOP caution message appeared shortly after passing approximately 80 kts. Around 90 kts; I recognized the caution and assessed that; while it might not immediately affect the safety of the takeoff; it represented a potential loss of directional control at high speed. By 100 kts; I announced; 'Abort; my controls;' and initiated a rejected takeoff.During deceleration; there was little to no directional control available through rudder inputs; and differential braking was required to maintain runway alignment. Once at a safe speed; I exited the runway onto an adjacent taxiway and brought the aircraft to a complete stop. I then made a public address to the passengers; informed the flight attendants of the situation; and completed the applicable QRH procedures and checklists.I notified Dispatch; Maintenance Control; and local Operations to coordinate a return to the gate. We were able to taxi under our own power using differential braking; as the taxiway led directly toward the terminal gate area. The aircraft returned to the gate; and passengers deplaned without further incident.It was determined that the event involved a loss of nosewheel steering capability; as confirmed by both the STEERING INOP caution message and the lack of steering response during rollout.Cause: The event was caused by a loss of nosewheel steering authority for reasons that remain undetermined. Maintenance later assumed control of the aircraft; and the flight crew was reassigned to another airplane; so the specific cause was not confirmed.Contributing factors included a lengthy ground delay of approximately three to four hours due to maintenance activity involving a deferred APU door; as well as time pressure from the First Officer nearing the end of his flight duty period (less than 30 minutes remaining before takeoff). Although the STEERING INOP message alone might not have directly compromised the safety of the takeoff; I considered it a directional control concern during a critical phase of flight. Given the gusty winds (210° at 20 gusting 30) and the risk of losing steering authority; I determined that rejecting the takeoff was the safest course of action.Suggestions: This event reinforces the importance of rejecting a takeoff for any directional control concern; even when the indication appears minor or ambiguous. To help prevent similar occurrences in the future:Provide additional guidance or training emphasizing appropriate decision-making for steering-related alerts during takeoff.Encourage maintenance follow-up procedures that prioritize troubleshooting of intermittent steering faults before dispatch.Continue to emphasize effective crew resource management and maintaining a conservative approach when operational or time pressures exist.Although this event resulted in passenger frustration due to additional delays; there were no safety impacts to passengers; crew; or ATC operations.