Who would have thought that the winner of the next big contest for the U.S. Senate seat from Texas would hinge on the candidates’ “likability”?

Democrat Beto O’Rourke is challenging Republican incumbent Ted Cruz in 2018. Cruz was supposed to win re-election in a walk. He represents Texas in the U.S. Senate, one of the nation’s most reliably Republican states.

Something happened, though, on Cruz’s re-election waltz. He ran into a guy who seems to be throwing conventional wisdom out the window. O’Rourke is conducting an essentially positive campaign to date, speaking in vague terms about ridding Washington of the hyper-negativity that borders on hostility.

Meanwhile, Cruz is firing off barbs criticizing O’Rourke over his occasional potty mouth as a younger man.

He is managing to make O’Rourke eminently more “likable.”

Cruz stormed into the Senate six years and made an immediate national name for himself. He became one of those rare freshman senators who could be seen on TV constantly, at times seemingly in several locations all at once. He seemed to defy the laws of physics by being everywhere at the same time. What drove Cruz? Personal ambition. Therein lies what I believe has been Ted Cruz’s primary reason for serving in the Senate.

He ran for president of the United States halfway through his first term in the Senate, which by itself isn’t all that unusual: Barack Obama did the same thing, too.

But Cruz comes off as harsh, self-centered and blinded by personal ambition. Indeed, Donald Trump may have spoken something approaching the truth when he said during the 2016 presidential campaign that “no one likes” Cruz in the Senate.

What was supposed to be a cakewalk to re-election for the GOP incumbent senator has turned into a journey fraught with peril.

It all might be decided on likability.