Ted Cruz. I think near term, 2018 was a high water mark for TX Dems. Cruz wasn't very popular, was caught sleeping on O'Rourke who visited every county and turbocharged Dem turnout while R voters stayed home. Beyonce has no hope of matching that (let alone winning) and Beto will likely not even come close to that performance in his gubernatorial bid next year.
I didn't follow TX SEN 2018, though I obviously know it was very close. But I didn't know Beto visited all 254 counties in TX. You mean to say he visited all those square-shaped, 80%+ Republican counties with under 30,000 people?