WASHINGTON, D.C. (CBSDFW.COM/AP) – Texas freshman Congressman Colin Allred is throwing his weight behind Joe Biden for president — making him the 10th member of the Congressional Black Caucus to endorse the Democratic presidential candidate.

Allred’s decision underscores the former vice president’s advantage with a crucial party constituency less than a month before 2020 voting begins.

READ MORE: State Fair Taking Extra Measures To Keep Guests Safe

Allred, who flipped a Republican district in the 2018 midterms, is the latest Texas Democrat to back Biden after initially siding with Texan Julián Castro, who ended his presidential bid January 2 and has since endorsed one of Biden’s more progressive rivals, Massachusetts Sen. Elizabeth Warren.

Rep. Colin Allred, D-TX, speaks in front of the U.S. Supreme Court. (credit: Mandel Ngan/AFP via Getty Images)

“This is a really dangerous time for the country,” Allred told The Associated Press, pointing to a recent flareup with Iran. “We have to nominate someone in the Democratic Party who can unite the country and heal the divisions that are going on.”

Allred, a former Obama administration lawyer and NFL linebacker, sidestepped Castro’s endorsement of Warren, but said Biden best represents the Democratic mainstream, and he warned that going too far left could doom the party in November. He pointed to midterm victories like his own, when he won 52% of the vote to defeat Republican Pete Sessions and become the first Democrat and first African American to represent his suburban Dallas district.

“We’ve always done our best when we’ve nominated candidates who’ve attracted independents and disaffected Republicans,” he said. “That’s what President Obama did. That’s what Bill Clinton did. When we’ve pursued the route of ideological purity it’s tended not to work, particularly at the national level.”

That argument highlights perhaps the starkest divide in Democrats’ 2020 nominating fight.

Democratic Presidential candidate Joe Biden delivers a foreign policy statement on Iran at Chelsea Piers in New York on January 7, 2020. (credit: Timothy A. Clary/AFP via Getty Images)

To Biden’s left, Vermont Sen. Bernie Sanders’ top House freshman endorsement comes from Rep. Alexandria Ocasio-Cortez, a New Yorker who has become a face of the progressive movement after defeating Democrats’ No. 3 House leader in a 2018 primary.

Warren touts House freshmen including Boston’s Ayanna Pressley and Katie Porter of California. Pressley, like Ocasio-Cortez, rode a progressive uprising to oust an entrenched Democrat in a primary. Porter defeated a suburban Republican, just as Allred did, but she’s made her mark in Washington as an outspoken advocate for the working class, following in Warren’s footsteps with withering examinations of bank executives during hearings on Capitol Hill.

READ MORE: Officials: Man Suspected Of Making Threats Against Texas Lawmakers Arrested

All those Democrats argue that defeating President Donald Trump requires a nominee who can capitalize on progressives’ energy.

Allred suggested Democrats’ left flank takes too narrow a view of internal party policy fights, missing how most Americans judge issues. “This is not just theoretical policy discussion,” he said. “People are driven by values and people who appeal to those values. That’s what we’re trying to do, is make Americans understand that we’re on their side.”

In addition to Allred, Texas Democrats Marc Veasey and Rep Eddie Bernice Johnson have also endorsed Biden.

Biden had trailed California Sen. Kamala Harris in CBC endorsements, and he’s still working to win over some of those members who supported Harris, the lone black female candidate before she suspended her campaign in December. But none of the remaining candidates is anywhere close to Biden in Black Caucus support; Biden also holds a commanding lead nationally among black voters, a group that will play a significant role in the nominating fight once the calendar moves beyond overwhelmingly white Iowa and New Hampshire.

MORE NEWS: State Fair Offers Hundreds Of Free Acts, Shows And Exhibits

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)