Democratic presidential candidate Bernie Sanders is sharpening his focus on the Texas primary with early voting underway, planning four rallies in the state this weekend and naming more staff here.

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Sanders has scheduled rallies Saturday in El Paso and San Antonio and Sunday in Houston and Austin. The Saturday rallies come the same day that Nevada holds its caucus, in which Sanders is expected to do well. He will be joined in San Antonio and Houston by actor Kendrick Sampson, a Houston native, according to the campaign.

Sanders' busy weekend here comes a week after he held a Dallas-area rally where he voiced confidence he would win Texas, a delegate-rich state that votes with over a dozen others on March 3, or Super Tuesday.

The latest additions to Sanders' Texas campaign, first shared with The Texas Tribune, include two senior staffers, field director Michael Ortiz and political director Stephen Brown, as well as a third staffer, political coordinator Jose Zayas Caban. Ortiz was Sanders' deputy field director in New Hampshire, while Caban comes from the candidate's Iowa team. Brown, who is from Fort Bend County, was the 2014 Democratic nominee for railroad commissioner.

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At the same time, Sanders' campaign has promoted Chris Chu de León to Texas state coordinator after he served as state field director. The campaign now has a dozen people on its Texas staff.

This story is part of the series: Texas 2020 Elections.

In addition to the new hires and rallies, Sanders' campaign told the Tribune it is naming two more state co-chairs: Joca Marquez, a member of the San Marcos City Council, and former state Rep. Marisa Marquez, who was the only state lawmaker to back Sanders when he ran in the 2016 primary.

The latest University of Texas/Texas Tribune poll, released a week ago, found Sanders leading former Vice President Joe Biden by 2 percentage points in Texas, within the margin of error. Another Texas survey that came out Thursday gave Sanders a similarly small advantage over Biden.

While most candidates beside Sanders have not been spending much time in Texas lately, they are not ignoring the state. On Friday morning, Elizabeth Warren's campaign rolled out the endorsement of Harris County Judge Lina Hidalgo.

“Whether it’s combating climate change or increasing opportunities for minorities in small business, Elizabeth has a plan for that," Hidalgo said in a statement. "But my support for her is not because of her plans, it’s because of who she is. The Elizabeth Warren you speak with one-on-one is the same Elizabeth you see on the stump."

Michael Bloomberg has visited the state the most in recent weeks — five times since launching his campaign in late November — and continues to build out easily the largest Texas primary operation. His campaign sent a group of national surrogates to Texas earlier this week as early voting began, including former Los Angeles Mayor Antonio Villaraigosa and former Philadelphia Mayor Michael Nutter. Bloomberg's campaign also announced 10 new Texas endorsements Wednesday, including state Rep. Richard Peña Raymond of Laredo, who will serve as a state co-chair.

Biden last visited the state in mid-January, mainly for fundraising. However, he continues to maintain the biggest endorsement list in Texas — and he added U.S. Rep. Sylvia Garcia of Houston to it on Wednesday. Garcia, a former House impeachment manager, is the sixth member of the Texas congressional delegation to back Biden.

Like Bloomberg's campaign, Sanders' has also dispatched surrogates to Texas during early voting, which ends in a week. Civil rights activist Shaun King was in Texas on Friday to campaign for Sanders in Houston and Dallas.

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Disclosure: The University of Texas has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.