U.S. President Donald Trump threatened to strip Harvard of its tax-exempt status on Tuesday and said the university should apologize, a day after it rejected what it called unlawful demands to overhaul academic programs or lose federal grants.

On the campus and beyond, some hope that other universities will "grow a spine" and stand up to the administration.

Tensions are rising across American academia as the Trump administration froze over $2 billion in multi-year grants and contracts at Harvard University after its leaders refused to make key policy changes the White House also is demanding of other elite US colleges.