Freedomworks, a national Tea Party-affiliated group, has endorsed Rep. Don Manzullo (R-Ill.) over Rep. Adam Kinzinger (R-Ill.), making it the latest major group to weigh in on the primary.

"It's not difficult to recognize that Manzullo is the fiscal conservative and Kinzinger is the moderate," said Freedomworks PAC Executive Director Max Pappas in a statement. "When it came to the big spending votes last year, Don Manzullo said, 'Enough is enough.' Kinzinger too often voted for more of the same."

The group's endorsement comes a day after House Majority Leader Eric Cantor (R-Va.) and Rep. John Shimkus (R-Ill.) threw their support to Kinzinger. House Republican leaders have identified Kinzinger as a rising star and have been increasingly public in helping his campaign against the longtime congressman.

"We work on a regular basis with both Adam Kinzinger and his opponent. We join our colleague Congressman Aaron Schock of Illinois in the judgment that Adam Kinzinger is the right choice to keep advancing our conservative movement," Cantor and Shimkus said in endorsing Kinzinger.

The two were thrown together after the Democrat-controlled restricting process was finished. Their primary has turned into a funhouse-mirror image of many races between older establishment Republicans and younger Tea Party challengers.

Kinzinger won his seat in 2010 with strong Tea Party support but has developed a more centrist voting record since he entered the House, making establishment Republicans happy but angering his Tea Party base.

His decision to quit the conservative Republican Study Committee and join the centrist Tuesday Group after a fight between the RSC and House GOP leaders pleased Boehner but infuriated groups like Freedomworks, which cite that switch as one reason they've endorsed Manzullo. He's also angered local Tea Party groups with some of his votes; the Illinois Tea Party, a confederation of statewide Tea Party groups, is also backing Manzullo.

Illinois's primary is on March 20.