Texas Rep. Joaquin Castro Joaquin CastroFlorida Democrat asks FBI to investigate anti-Semitic, racist disinformation Hispanic Caucus members embark on 'virtual bus tour' with Biden campaign Hispanic caucus report takes stock of accomplishments with eye toward 2021 MORE (D) and his brother, former Secretary of Housing and Urban Development Julián Castro, will join Rep. Beto O'Rourke Beto O'RourkeJimmy Carter says his son smoked pot with Willie Nelson on White House roof O'Rourke endorses Kennedy for Senate: 'A champion for the values we're most proud of' 2020 Democrats do convention Zoom call MORE (D-Texas) at stops along the Texas border, O'Rourke's Senate campaign team announced Thursday.

Castro brothers are hitting the trail w/ @BetoORourke pic.twitter.com/ig3TTDc1fd — Andrea Drusch (@AndreaDrusch) September 20, 2018

The trip with the Castro brothers will come after O'Rourke's first debate with incumbent Sen. Ted Cruz Rafael (Ted) Edward CruzCruz blocks amended resolution honoring Ginsburg over language about her dying wish Trump argues full Supreme Court needed to settle potential election disputes Press: Notorious RBG vs Notorious GOP MORE (R), scheduled for Friday.

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Polls have shown Cruz and O'Rourke in a tight race in deep-red Texas, and the Hispanic vote could be key to November's results.

Cruz is getting support from 45 percent of likely Hispanic voters, 9 percent shy of the 54 percent who support O'Rourke, according to a Quinnipiac University poll released this week.

Julián Castro, a former mayor of San Antonio, sits on the board of directors for Voto Latino, a nonprofit that encourages more political activity among Hispanics. He was considered as a potential vice presidential running mate to Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE in 2016 in part because of his appeal to Hispanic voters.

He has also said that he is considering running for president in 2020, telling CSPAN in May that he would make a decision on whether to seek the nomination after the midterms.

His brother, Joaquin, has served in the House since 2013 as a representative for Texas's 20th Congressional District, which includes part of San Antonio.