A California Democrat hit back at President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's eldest son on Thursday after Donald Trump Jr. Don John Trump'Tiger King' star Joe Exotic requests pardon from Trump: 'Be my hero please' Zaid Jilani discusses Trump's move to cancel racial sensitivity training at federal agencies Trump International Hotel in Vancouver closes permanently MORE accused the candidate of links to extremist groups through the Council on American-Islamic Relations (CAIR), a Muslim civil rights group.

Ammar Campa-Najjar, a Democrat running to replace Rep. Duncan Hunter Duncan HunterDCCC reserves new ad buys in competitive districts, adds new members to 'Red to Blue' program Wife of former Rep. Duncan Hunter sentenced to 8 months of home confinement Harris endorses Democrat in tight California House race MORE (R-Calif.), tweeted a picture of himself meeting then-candidate Donald Trump in 2015, questioning Trump Jr. whether he could explain why his father was meeting with a so-called "terrorist sympathizer" if the allegations were true.

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His tweet followed a message from Trump Jr. calling CAIR, which Campa-Najjar has donated to, a "radical Islamist group."

"Hey @DonaldJTrumpJr, before retweeting @BreitbartNews charged allegations — might want to check with POTUS. I was given security clearance from the FBI in 2013 and met with @realDonaldTrump in 2015. Do you think your father met with a terrorist sympathizer? Doubt it," responded Campa-Najjar.

Hey @DonaldJTrumpJr, before retweeting @BreitbartNews charged allegations — might want to check with POTUS.



I was given security clearance from the FBI in 2013 and met with @realDonaldTrump in 2015.



Do you think your father met with a terrorist sympathizer? Doubt it. pic.twitter.com/ItskH73ixM — Ammar Campa-Najjar (@ACampaNajjar) October 11, 2018

CAIR has fended off allegations from right-wing organizations including Breitbart News in the past over its alleged affiliations with Hamas, the Palestinian militant group designated as a terrorist organization by the U.S. CAIR has repeatedly denied any affiliation with Hamas, and has condemned its terrorist activities.

Campa-Najjar's race against Hunter received nationwide attention after Hunter was indicted earlier this year on charges of misusing about $250,000 in campaign funds, while vowing to remain in the race.