According to this poll, Cornyn is polling *lower* than the percentage of the vote he just received in a race with several candidates splitting the vote. Meaning some of those who just voted for him are no longer supporting him in less than a week and he’s getting 0% of the votes from the other candidates’ supporters. He only gets to a tie in the support he already received last week if Trump endorses him according to this poll.
There are still lots of undecideds i would guess they would go to Paxton more than Cornyn who is - in my opinion - just less appealing.