Texas A&M University’s president is stepping down amid a controversy roiling the campus. In a statement issued Friday, Mark A. Welsh III did not say if political pressure and criticism he and the school received after a video showing a confrontation between a professor and a student over the teaching of gender identity in a children’s literature class played a role. Welsh said it had become clear to him in recent days that it was time for him to step down as leader of one of the largest universities in the country. Welsh’s resignation will take effect on Friday. The professor has since been fired.