The pro-business group's endorsement could mean big money for Hasner. The Chamber has been spending heavily on ads boosting candidates it supports and attacking incumbent Democrats in congressional races across the country.

Hasner is running in a redrawn Florida district currently held by Rep. Allen West (R-Fla.), who is running for reelection in a different district. Hasner will face the winner of the Democratic primary, where Lois FrankelLois Jane FrankelDem lawmaker brings coat hanger to briefing to denounce Trump's Supreme Court pick The Hill's Morning Report — Sponsored by Better Medicare Alliance — Protests and anger: Washington in turmoil as elections near Dem generation gap widens MORE has the early lead.