In the latest sign that Texas can no longer be counted a reliably red state, former U.S. Rep. Beto O'Rourke of El Paso, former Vice President Joe Biden and U.S. Sen. Bernie Sanders of Vermont are running neck-and-neck with President Donald Trump in trial 2020 presidential matchups in the state, according to results of a Quinnipiac University poll released Thursday.

Former San Antonio Mayor Julián Castro and two other Democrats who have announced their candidacies for president — U.S. Sens. Kamala Harris of California and Elizabeth Warren of Massachusetts — lag a little behind Trump in the very early test runs.

O'Rourke is also in a dead heat with U.S. Sen. John Cornyn, R-Texas, in a prospective 2020 Senate race that O'Rourke, who will announce shortly whether he is going to run for president, appears to have little interest in making.

The survey of 1,222 Texas voters was conducted Feb. 20-25 and has a margin of error of plus or minus 3.8 percentage points.

Quinnipiac found Trump leading both O'Rourke and Biden by the same margin — 47 percent of respondents said they would vote for Trump today over O'Rourke or Biden, who both received 46 percent of hypothetical votes. Trump edged Sanders at 47 to 45 percent and led Castro, 46 to 41 percent, and both Harris and Warren, 48 to 41 percent.

Sanders, who ran for the Democratic presidential nomination in 2016, has declared his candidacy for president. Biden has not yet declared his intentions.

On a 2020 Senate race, the poll found O'Rourke locked in a 46-46 percent tie with Cornyn.

On Wednesday, O'Rourke issued a statement in which he said he and his wife, Amy, "have made a decision about how we can best serve our country. We are excited to share it with everyone soon."

The Dallas Morning News reported Wednesday that O'Rourke had ruled out a Senate race and was likely to enter the presidential contest. Peter Brown, assistant director of the poll, wondered whether there was another Texas Democrat who could poll as well against Cornyn.

In a conference call with Texas reporters on Wednesday, Cornyn, who has been taking the possibility of an O'Rourke challenge very seriously and gotten a quick start on his re-election campaign, said of O'Rourke, "it really makes no difference to me what he decides to do."

"We’re going to be prepared for whoever decides to run and whoever is nominated for the Senate by the Democrats in 2020," Cornyn said.

Remarkably, according to the poll, O'Rourke, who was little known in the rest of the state before his Senate campaign, is far better known by voters than Cornyn, who will be seeking a fourth six-year term in the Senate and before that had served as Texas attorney general and as a justice of the Texas Supreme Court.

Brown said it might be good news for Cornyn that he is not better known because he has "more upside" than a more clearly defined candidate.

Of Cornyn, opinion was 34 percent positive to 21 percent negative, with 43 percent passing for lack of sufficient knowledge about him and 1 percent not answering.

The poll found that O'Rourke was viewed favorably by 44 percent of respondents, and unfavorably by 40 percent, with 15 percent saying they haven't heard enough about him to make a judgment and 1 percent refusing to answer.

Trump's rating was 47 percent positive, 49 percent negative, 10 percent not knowing enough to say, and 2 percent refusing to say.

Biden had the most positive rating, with 48 percent favorable, 38 percent unfavorable, 12 percent not knowing enough to say and 2 percent refusing to say.

Sanders is viewed negatively overall, with 47 percent holding a negative opinion and 41 percent a positive opinion, 10 percent holding no opinion, and 1 percent refusing to answer.

Still, the fact that Sanders, a self-described democratic socialist, was in a virtual tie with Trump in a head-to-head matchup, with Sanders leading Trump among independent voters, 48 to 41 percent, suggests the Republican grip on Texas might be tenuous.

"It's a poll almost two years before an election," Brown cautioned of the survey results.

But, if Texas, the second-largest state, were to go Democratic in a presidential election, Republicans could be hard-pressed to assemble an Electoral College majority.