PRINCETON, N.J. — By the time he was a senior at Princeton University in 1992, Ted Cruz had developed an arsenal of rhetorical skills and theatrical gestures that made him one of the most polished performers on the college debate circuit. So when he reached the quarterfinals of the national championships at M.I.T., with the title that had eluded him so far now in sight, he decided to try to knock his Harvard opponents off balance with one of his favorite tricks.

Instead of the regular practice of defending his proposed topic — the merits of mind-reading — Mr. Cruz let his adversaries choose which side to argue. But the tactic, intended to highlight his confidence, backfired. As he waited for them to decide, the two Harvard students conspicuously dithered, eating up Mr. Cruz’s allotted speaking time as they whispered and searched their pockets for a coin to flip.

The audience, now on to the stalling tactic, chuckled as Mr. Cruz snapped: “Gentlemen! You must have decided by now.” But he and his partner never recovered, and the national championship for which he had worked so hard went to someone else.