U.S. Rep. Tom McClintock has a four-point lead over his Democratic challenger Jessica Morse in the race for California’s Congressional District 4, according to an internal poll commissioned by Morse’s campaign that was released on Wednesday.

The poll, conducted by the Washington, D.C.-based Clarity Campaign Labs, LLC, had the five-term Republican incumbent leading Morse 49 percent to 45 percent heading into the Nov. 6 general election.

Clarity Campaign Labs stated the results came from a survey of 840 registered voters in the district conducted on October 15 and 16. It had a 3.4-percent margin of error.

Morse’s campaign released a statement with the poll results calling this race the “toughest challenge” McClintock has faced since he was first elected to the House of Representatives in 2008, when he narrowly beat Democrat Charlie Brown by a half of a percent.

McClintock has won every election since 2008 by 20 points or more over his opponents, including a Republican challenger in 2014.

The Morse campaign cited the results of the poll in a fundraising email sent to supporters a day before they were publicly released.

When asked for a response, McClintock’s campaign manager Jon Huey sent a link to a tweet he put out on Wednesday with results from two internal polls the campaign conducted from Sept. 8 to 10 and Oct. 10 to 11 that both had McClintock with a nearly 20-point advantage over Morse.

Huey did not immediately respond to an email on Wednesday asking how the polls were conducted and who conducted them.

Morse will have to overcome a 13-point Republican advantage in the district, which covers six rural Sierra Nevada counties and portions of four others. Tuolumne and Calaveras counties were added in 2012 through the state’s independent redistricting process.

The Cook Political Report, an nonpartisan election forecaster, had the district labeled as “likely Republican” in the upcoming election. President Donald Trump won the district with 54 percent in the 2016 presidential election against Democratic nominee Hillary Clinton.

In the statement released Wednesday, the Morse campaign noted the Clarity Campaign Labs poll had Morse with a 63 percent to 31 percent lead over McClintock among independent and no party preference voters.

Contact Alex MacLean at amaclean@uniondemocrat.com or (209) 588-4530.