Rough and tumble. Hammer and tongs. In the race for this year’s Republican nomination, Donald Trump has not hesitated to attack and ridicule many of his opponents, and some of them have teed up attacks on him, only to hold back when they seemed to help rather than hurt him.

Ted Cruz is the one candidate who has conspicuously refrained from attacking the national front-runner, gliding along in his wake. “As others have thrown rocks and others have tossed insults, I haven’t reciprocated,” Cruz, who is first in the Washington Examiner‘s presidential power rankings, said Jan. 5.