The U.S. Chamber of Commerce endorsed GOP Rep. Justin Amash’s primary challenger in Michigan’s 3rd District.  

The group’s support could translate into television airtime for Brian Ellis, a former East Grand Rapids School Trustee, before the Aug. 5 primary. The primary has become one of this cycle’s top battles inside the GOP, with the party’s libertarian wing backing Amash and national business interests boosting Ellis.  

“The U.S. Chamber is proud to endorse Brian Ellis’ congressional campaign to represent Michigan’s 3rd congressional district. Both candidates in the primary sought our endorsement, and the choice in support of Ellis on pro-growth issues was clear,” U.S. Chamber Senior Vice President and National Political Director Rob Engstrom said in a Thursday statement.  

Ellis more raised twice as much as Amash in the second quarter — some of which was self-financed. But Amash retained a cash-on-hand advantage, according to CQ Roll Call’s House Fundraising Chart . He also has the support of the Club for Growth.  

The U.S. Chamber of Commerce has already spent more than $14 million on races this cycle, according to the Center for Responsive Politics.  

The race is rated as Safe Republican by Rothenberg Political Report/Roll Call.