An imaging member, such as a negative-working printing plate, can be prepared using a hydrophilic heat-sensitive imaging layer comprised of a hydrophilic heat-sensitive, crosslinked vinyl polymer containing recurring organoonium groups. The imaging member can also include a photothermal conversion material such as carbon black or an infrared radiation absorbing dye. The heat-sensitive polymer has recurring units containing an organoammonium, organophosphonium or organosulfonium group that reacts to provide increased oleophilicity (ink receptivity) in response to heat. Heat is preferably generated by laser irradiation in the IR region of the electromagnetic spectrum. The heat-sensitive polymer is considered “switchable” in response to heat. The imaging member can be used in printing methods without the usual wet processing steps.