NASHVILLE, Tennessee–In an exclusive interview with Breitbart News, GOP front runner Donald Trump is firing back at the Club for Growth.

“They’re a pack of thieves,” Trump told Breitbart News as he was leaving Nashville’s Rocketown facility. He had just finished delivering a high-energy speech to an overflow crowd of more than 1,000 people.

Trump was attending the annual convention of the National Federation of Republican Assemblies, which describes itself as “the grassroots Republican wing of the Republican Party.”

“They [the Club for Growth] came to my office looking for money. I turned them down. That’s why they’re after me,” Trump told Breitbart News.

Earlier in the week, the Club for Growth attacked Trump for his proposal to penalize Ford Motor Company for putting a car manufacturing plant in Mexico rather than Tennessee.

“Donald Trump’s threat to impose new taxes on U.S. car companies will hurt the American economy and cost more American jobs,” David McIntosh, President of the Club for Growth, said in a statement.

“It should thrill liberals and Democrats everywhere that Trump wants to create new taxes and start a trade war to force American companies to work where he demands,” McIntosh added.

Trump stopped specifically to address Breitbart’s question as he moved down the exit aisles surrounded by throngs of supporters.

“I love Breitbart News. This is going to be a good question,” Trump said.

Trump did not pull any punches when asked if he had a message for the Club for Growth in response to its attacks.

Other candidates might shy away from calling out their critics so bluntly as “a pack of thieves,” but for Trump it was just another opportunity to take the battle to the opposition.