Rep. Scott Peters, running for re-election in a hotly contested race, is something of a political unicorn: a Democrat endorsed by the U.S. Chamber of Commerce.

The Chamber of Commerce announced it will back Peters over Republican Carl DeMaio in California's 52nd Congressional District, which includes parts of San Diego — one of the seats Republicans have targeted as a prime pick-up opportunity in this midterm election cycle.

“We believe that your re-election to the U.S. House of Representatives will help produce sustained economic growth, help create jobs, and get our country back on track,” Chamber President Thomas Donohue wrote to Peters, as reported by the U-T San Diego. “We will encourage the business community to vigorously support your candidacy.”

Although the Chamber of Commerce is technically a pro-business group that could support candidates of either party, it tends to heavily favor Republicans. That trend has held so far in this election cycle: The Chamber has so far spent $13 million on ads to boost Republicans and another $2 million attacking Democrats, according to, which tracks campaign spending. Meanwhile, the Chamber of Commerce has spent just $1 million attacking Republicans (in GOP primaries), and has committed no money to supporting Democrats. The Chamber has, however, endorsed two other Democrats so far this cycle.

The group's stamp of approval will likely be a major boon for Peters, who narrowly won his seat in Congress in 2012 and is expected to struggle to hold on to it this year. Peters faces stiff competition from DeMaio, a former San Diego City councilman who has received national attention as one of a few openly gay Republican candidates this year.