Julian Castro, who may be eyeing a 2020 presidential run, used a vulgar Spanish-language slang word on Friday evening to smear President Donald Trump after he pardoned former Maricopa County Sheriff Joe Arpaio.

The former San Antonio mayor and President Barack Obama’s Housing and Urban Development Secretary tweeted: “Trump in one word tonight: #pendejo.”

The nasty word is understood to mean “dumbass” or “asshole” in areas like Southern California and Texas where those of Mexican descent are dominant among Hispanics to describe an “idiot” or a “contemptible person.”

Castro may be trying to rile up his base of left-wing Latino voters as he potentially maps out a potential 2020 challenge. He also tweeted that “Trump’s Arpaio pardon another example of just how morally bankrupt Trump is. What a national embarrassment they both are.”

Trump in one word tonight: #pendejo — Julián Castro (@JulianCastro) August 26, 2017

Trump's Arpaio pardon another example of just how morally bankrupt Trump is. What a national embarrassment they both are. #failedPOTUS — Julián Castro (@JulianCastro) August 26, 2017

Breitbart News has pointed out that Castro, who just formed a political action committee, may be a formidable Democrat in 2020: