"We need to narrow the field and unite as Democrats to defeat (President Donald) Trump in November 2020.
That's why I believe I'm moving my support to Vice President Joe Biden," Gonzalez, who represents the Texas 15th Congressional District, said.
Gonzalez called the former vice president a "steady ship" with White House experience who can defeat Trump.
In response to the pulled endorsement, Castro campaign spokesman Sawyer Hackett said, "Congressman Gonzlez is entitled to endorse whichever candidate he feels represents his values.
I can't believe that you said -- two minutes ago -- that they had to buy in and now you're forgetting that.