issue a challenge to

serving or tending to provoke, excite, or stimulate; stimulating discussion or exciting controversy

needed encouragement

something that incites or provokes; a means of arousing or stirring to action

provoke someone to do something through (often false or exaggerated) promises or persuasion

cause (a stream or river) to erode, as by an uplift of the land

stimulate to remember

provoke or stir up

try to stir up public opinion