Rep. Kerry BentivolioKerry BentivolioIndiana Republican: Leaders duped me Reindeer farmer saves 'cromnibus' with yes vote High drama as .1T spending package advances by one vote MORE (R-Mich.) is lashing out at the U.S. Chamber of Commerce, which has endorsed his primary opponent, accusing the business group of being "in the pocket of communist China."

Bentivolio's office put out a statement saying he was rejecting the Chamber's "Spirit of Enterprise Award," which the group gave to more than 200 congressmen this spring for voting with the Chamber's interests. The organization has since backed businessman Dave Trott (R) in his primary election against Bentivolio.

Bentivolio and his chief of staff had harsh words for the Chamber, which has supported immigration reform.

"The US Chamber is in the pocket of Communist China and big companies seeking cheap labor in the United States," Bentivolio chief of staff Rob Wasinger said in a statement put out by his Washington office and forwarded by his campaign. "We think it is morally repugnant for the chamber to pursue, as a matter of public policy, initiatives which exploit the poor and oppressed, just so they can keep labor costs down for their fortune 500 member companies," Wasinger continued.

Bentivolio took shots at the Chamber as well. 

"The Chamber of Commerce is beholden to special interests and has long since forgotten the main street businesses that struggle everyday to make payroll and keep their company afloat," Bentivolio said. "It is with great pride that I reject their award, and call on them to stand on the side of America, instead of on the side of China and corporate interests seeking to exploit people for profit. I am with main street, not Wall Street."

Chamber officials point out that Bentivolio came to accept the award and posed for a photo with the group's president last spring.

"The Chamber is proud to have endorsed the next Congressman from MI-11, Dave Trott," Chamber spokeswoman Blair Holmes said in an email.

The freshman House member, dubbed the "accidental congressman" by some after he won a seat because then-Rep. Thaddeus McCotter (R-Mich.) failed to qualify for the ballot, is facing a steep uphill challenge ahead of his Aug. 5 primary.

Trott has raised big money for his campaign, and Bentivolio has done himself no favors in the race. Bentivolio has raised almost no money, his 2012 campaign manager is suing him for failing to pay his salary, and his original 2014 campaign manager also resigned earlier this year.

This post was updated at 7:00 p.m.