As WaPo's Dave Weigel rightly notes, this is only the second time that Cruz appears to have gotten genuinely angry during this presidential campaign -- the first being when The Post published a cartoon that cast his two young daughters as monkeys and the Texas senator as an organ grinder.
He should do it more often.
The truth of this campaign is that Trump has channeled and mirrored the anger of the Republican electorate. All of the other candidates have tried to nod to it, say they understand it, and then try to defuse it. But, when you are mad as hell, the last thing you want is for someone to tell you to "calm down." That ramps UP your anger, rather than lowering it. It comes across as condescending and out of touch.
Trump innately understands that to benefit from the anger coursing through the Republican electorate, you have to match it. You have to get angry yourself -- and show it. Hell, let out a curse word or two. Yell "Get 'em out of here!" at a protester. Show that you are willing to throw a punch -- even if you never do.
Cruz, for much of the race, has acted like the college debate champion he is. He makes his points -- whether in debates or on the stump -- with conviction. He rails against the Obama administration. He criticizes Trump for an alleged lack of conservative bona fides. But it's always at a remove. It's an intellectual argument, not an emotional one. It feels like he is reading off a script, not speaking from the heart.
Cruz's response to Trump's goading of his wife, on the other hand, feels visceral and real. That's a good thing for Cruz, who struggles with likability on the campaign trail at least in part because people have a hard time getting a sense for who he really is. (Sidebar: On the other end of this spectrum but no less effective in terms of humanizing the senator was when Cruz read "Green Eggs and Ham" to his daughters during his Senate filibuster.)
Cruz and his campaign team, to his and their credit, seem to grasp the possibility that his smackdown of Trump on Thursday might be a pivot point in the race. Soon afterward, Cruz sent a tweet touting the moment from his account.
Sometimes, the only way to answer outrage and anger is with outrage and anger. Ted Cruz may have learned that lesson today.