These charts are from the latest University of Texas / Texas Tribune Poll -- done between May 31st and June 9th of a sample of 1,200 registered voters in Texas. It has a margin of error of 2.83 (and a 4.46 margin of error for Democrats and Democratic-leaning Independents).
In the past, I brought you an Emerson College Poll and a Quinnipiac University Poll that showed Texas may well be in play for 2020 -- with Democrats having a chance to carry the state (at least in the presidential race). This UT / TT poll shows the same thing.
When asked if they would vote to re-elect Donald Trump, the registered voters were split -- with 50% saying they definitely or probably would vote for Trump and an equal 50% saying they definitely or probably would vote against Trump. It doesn't get any closer than that. Both Trump and the Democrats have a lot of work to do in Texas before November of 2020, because the state could go either way.
And who would Texas Democrats (and Independents) choose to represent the Democratic Party in 2020? Right now, Joe Biden (23%) has an eight point lead over Beto O'Rourke (15%), a nine point lead over Elizabeth Warren (14%), and an eleven point lead over Bernie Sanders (12%). No other candidate scored in double-digits.
The bottom chart shows how familiar Texas Democrats and Independents are with the Democratic candidates.