For many years, Republicans portrayed colleges as bastions of leftism, awash in bias against conservatives and impervious to change. With Donald J. Trump’s victory to a second presidential term and a Congress potentially under unified G.O.P. control, Republicans are now poised to escalate their efforts to root out what they see as progressive ideology in higher education. The return to power of Mr. Trump comes at a vulnerable moment for higher education. Universities have been under increasing pressure from lawmakers, while public confidence in colleges has fallen.