WASHINGTON — Bernie Sanders is surging in Texas, just three weeks before voters start casting early ballots for their pick to take on President Donald Trump in November.

The Vermont Senator and self-described Democratic socialist has jumped to second in the state, cutting former Vice President Joe Biden’s lead to just two percentage points, according to a new Texas Lyceum poll released on Wednesday. Biden still leads the pack of Democratic presidential contenders at 28 percent, though his lead over Sanders — who stood at 26 percent — was within the poll’s 2.8 percentage point margin of error. Elizabeth Warren, a Massachusetts senator who lived for a decade in Texas, was in third at 13 percent.

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The poll shows Texans are still largely unsettled on who they support in key races — including the tight Democratic presidential primary and the still wide-open race to earn the party’s nomination to take on U.S. Sen. John Cornyn — even as some believe the Democrats can be more competitive in 2020 than they have been in a generation.

Sanders’ rise in Texas comes as his campaign announces a $2.5 million TV ad buy in Texas and California. It also coincides with his apparent surge nationally just days before Iowa caucuses, putting some moderate Democrats on edge.

“That has a lot of Democrats scared out of their minds,” said U.S. Sen. Ted Cruz — a Texas Republican who won the Iowa caucus in his 2016 presidential bid — who recently spoke about Sanders’ rise on his podcast. “There are an awful lot of Democrats who, I think, think if Bernie gets the nomination, it reelects Donald Trump, which is obviously not what Democrats are looking to do.”

But in Texas, at least, the Texas Lyceum poll suggests Sanders may have as good a shot as Biden at tackling Trump in November.

Though Trump polled better than all of the Democrats in the race, it found Sanders bringing in 47 percent to Trump’s 50. Biden was next, at 46 to 51. Warren had 44 to Trump’s 52.

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Sanders appears to be a big draw for Texas independents, 44 percent of whom would vote for him, compared to Trump’s 41 percent in a head-to-head matchup. Biden polls significantly worse with independents. Just 28 percent would vote for him, compared to 57 percent for Trump in a direct matchup.

Sanders, meanwhile, waded into another primary fight in Texas on Wednesday, endorsing Jessica Cisneros, a 26-year-old immigration attorney from Laredo, in her insurgent bid to unseat conservative Democrat Henry Cuellar, who’s held his South Texas district for 15 years.

More Information Texas primary election dates Feb. 3 - Last day to register to vote in time for the Democratic and Republican presidential primary elections Feb. 18 - The first day of early voting Feb. 28 - Early voting ends March 3 - Election day

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"This is the most important election in our lifetime and I'm proud there are so many candidates running for Congress who understand that real change comes from the bottom up, not the top on down," Sanders said. "Jessica is a strong advocate for real change and together we will build a movement to transform this nation so that it works for all our people."

The crowded Democratic primary for Senate, meanwhile, still appears to be wide open, with 42 percent of respondents still undecided. Former Air Force pilot MJ Hegar drew the most support with 11 percent. Next was state Sen. Royce West at 8 percent and longtime Austin labor organizer Cristina Tzintzún Ramirez at 7 percent.

“Texas is always a difficult state for candidates to introduce themselves to the voters due to its sheer size and multiple, large media markets,” said Joshua Blank, the poll’s research director. “But in a year in which the political oxygen has been sucked up by the Democratic Presidential Primary and impeachment, it’s clearly been a major challenge for those seeking to take on John Cornyn to break through with the Texas electorate.”

Cornyn’s campaign cheered the findings.

“Today’s poll confirms that Texas Democrats don’t know who their candidates are and don’t care,” said Krista Piferrer, a spokeswoman for the campaign. “We will be ready for whichever Elizabeth Warren clone emerges from the runoff in May.”

Texans, meanwhile, are still split on impeachment. Forty-five percent say the Senate acquit the president, though 44 percent say Trump should be removed from office. Nine percent are undecided.

Texans are mostly sour on the Trump’s job performance, however: Fifty two percent disapprove, while 47 percent approve. And 36 percent of Texans think the president is doing a “very poor job,” while just 27 percent think he is doing a “very good job.”

The 1,000-person telephone survey was conducted Jan. 10-19. It carries a margin of error of plus or minus 2.83 percentage points.

ben.wermund@chron.com