Even though I was repulsed by his behavior at the 2016 GOP convention, I'm glad Ted Cruz is in the Senate, because he's pretty much voted the right way on every bill.
Having said that, he's an absolutely terrible candidate. Texas is a solid Republican state where the Governor, the Lieutenant Governor, and the state's other Senator consistently win by double digits, sometimes in the 20+ range. If Ted Cruz can barely squeak by with 2-3% of the vote against a liberal kook like O'Rourke in a conservative state like Texas, he can pretty much forget about his chances for the Presidency.
The lieutenant governor and attorney general ran no better in 2018 than did TCruz. But George P. Bush did better than the other Republicans, except for Abbott.