The Democratic presidential challengers are letting it known that they have Kamala Harris’ back.

After Donald Trump Jr., President Trump’s eldest son, shared a tweet last Thursday questioning her “Blackness,” several of Harris’ Democratic rivals came to her defense.

On CNN’s State of the Union this past Sunday, Julián Castro called out Trump Jr. for spreading lies and renewing birther claims, that years ago his father aimed at former President Obama, but this time Trump Jr. is aiming at Harris. Castro called Trump Jr.’s tweet “disgusting” and said he considers him a “coward” for the incident.

Kamala Harris’ campaign is not here for the birther innuendo

“He’s giving voice to these racist utterances about Senator Harris,” Castro, Obama’s former Housing Secretary, said according to Mother Jones. “We need to dispel them immediately, and condemn them, and then not give them any more life because they are disgusting.”

Castro also tweeted that Trump Jr.’s retweet could be linked to “a right-wing effort to delegitimize an accomplished and powerful black woman.”

Trump Jr. shared this tweet from Ali Alexander last week: “Kamala Harris is implying she is descended from American Black Slaves. She’s not. She comes from Jamaican Slave Owners. That’s fine. She’s not an American Black. Period.”

In response to his retweet, Trump Jr. said: “Is this true? Wow,” presenting another birther claim to his millions of followers before deleting his tweet.

Georgia woman who faced backlash after taking a photo of a homeless dad issues apology

Other Democratic presidential hopefuls also bashed Trump Jr. for the retweet.

Harris “doesn’t have shit to prove,” tweeted Sen. Cory Booker (D-NJ).

“We all have an obligation to speak out and say so,” Sen. Elizabeth Warren (D-MA) tweeted last week. “And it’s within the power and obligation of tech companies to stop these vile lies dead in their tracks.”

“The same forces of hatred rooted in ‘birtherism’ that questioned ‘s American citizenship, and even his racial identity, are now being used against Senator . It’s disgusting and we have to call it out when we see it. Racism has no place in America,” Former vice president Joe Biden.

Harris’ campaign also fired back.

“This stuff is really vile and everyone should speak out against it,” Lily Adams, Harris’ campaign spokeswoman, tweeted Saturday.

Now let’s see which Republicans lambast Trump Jr.’s retweet.

Crickets.