An internal poll from embattled California Republican Rep. Duncan Hunter’s challenger Ammar Campa-Najjar showed the 50th District race in single digits.

The Tulchin Research poll found the five-term congressman ahead of his Democratic opponent, 51 percent to 42 percent. 

First elected in 2008 to succeed his father, Hunter won his most recent re-election with 64 percent of the vote. His father, also named Duncan Hunter, represented various iterations of the historically conservative Southern California district for 14 terms. 

“This poll shows voters are fed up with Congressman Hunter Jr.’s unethical behavior and are ready for real representation,” Campa-Najjar said in a statement. “Hunter’s record shows he’s beholden to special interests, not our interests. That all ends this November.”

A pre-primary San Diego Union-Tribune and 10News poll from May found Hunter with a significant lead over all his potential challengers. He ended up winning the top-two primary the following month with 47 percent of the vote to Campa-Najjar’s 18 percent. Two other Republicans and two Democrats split the remainder, with GOP candidates accounting for 62 percent of the total vote.

Since the introduction of California’s top-two election system in 2012, Hunter had always won a majority of the primary vote until this year. 

President Donald Trump carried the 50th District  in 2016 by 15 points. But the internal poll showed his approval numbers have dipped, with his favorable and unfavorable ratings both at 50 percent.

Hunter has been dogged by a federal criminal investigation for using campaign cash to pay for personal expenses such as family trips, flights and private school tuition.

Inside Elections with Nathan L. Gonzales rates the race Likely Republican.

The Tulchin Research poll surveyed 400 likely voters between July 17-23. The margin of error was plus or minus 4.89 percentage points.

Watch: McConnell Warns Russians to Keep Out of Elections, Schumer Wants More Than Words