Rep. Ruben Gallego Ruben GallegoHispanic caucus report takes stock of accomplishments with eye toward 2021 Senators call on Pentagon to reinstate funding for Stars and Stripes newspaper Hispanic Caucus campaign chief to mount leadership bid MORE (D-Ariz.) threw his support behind Sen. Kamala Harris Kamala HarrisTexas Democratic official urges Biden to visit state: 'I thought he had his own plane' The Hill's Campaign Report: Biden on Trump: 'He'll leave' l GOP laywers brush off Trump's election remarks l Obama's endorsements A game theorist's advice to President Trump on filling the Supreme Court seat MORE's Democratic presidential bid on Thursday, in a move that could help the California senator gain momentum as she slips in the polls.

Harris's campaign also announced that Gallego, who is a veteran and a member of the House Armed Services Committee, would serve as the campaign's national security chairman.

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“At a time when we are one tweet away from war, Kamala has demonstrated she has the tenacity, toughness, and judgment to restore American global leadership," Gallego said in a statement.

"Her bold plans to provide health care for all and citizenship for Dreamers shows that she’ll be a problem-solving president, and her track record of fighting for immigrants, consumers, veterans, and victims shows us that she truly does work for the people," he continued.

Gallego, who also sits on the Congressional Hispanic Caucus, will likely also help Harris target Latino voters in Arizona, which is slated to play a crucial role in 2020.

The congressman is the latest in a slew of lawmakers to endorse Harris. The senator is only second to former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE in endorsements, according to FiveThirtyEight.

However, Harris's support has dwindled in a number of recent polls.

A CNN poll released Wednesday, for example, showed Harris with 8 percent support, trailing Biden and Sens. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE (I-Vt.) and Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.) in the 2020 field.

Harris saw a surge this summer after a standout performance in the first round of Democratic debates, with a CNN poll finding her with 17 percent support in July.

She will be among 10 candidates taking the stage in Houston on Thursday evening for the party's next 2020 presidential debate.