Face the Nation host John Dickerson kicked off his interview Sunday with Sen. Ted Cruz (R-Tex.) with a line of questioning about President Trump's allegation that former President Obama illegally wiretapped Trump Tower during the election.

Citing a wealth of criticism of Trump's claim, Dickerson began by asking if Trump should simply drop the issue. "Well," Cruz replied, "these are serious allegations. I think they need to be looked into seriously."

After Cruz explained his reasoning, Dickerson pushed back. "You, in the campaign, went back and forth [with Trump] about the question of veracity," he said. "[Trump] told stories about your father and JFK's assassination. There seemed to be as much evidence for that as there is for this wiretapping claim. Can people trust this president?"

Cruz deflected the trustworthiness question entirely. "I don't know what basis the president has for these allegations," he said, reiterating once again his demand for an investigation. Dickerson let the matter go, moving on to health-care policy. Watch their full interview below. Bonnie Kristian