NASCAR team owner Richard Childress has resigned from the National Rifle Association’s board, the latest member to step down in recent weeks after a controversy over the group’s spending came to light.

In a letter announcing his resignation, which was first reported by NPR and obtained by CNN, Childress — who owns a successful racing team and company — said he wants to “fully focus” on his businesses, feeling that he owes that “to my employees, our partners, my family, and myself.

“Since proudly agreeing to serve on the NRA Board, I have supported the organization and its important mission to preserve and protect our Constitutional rights,” Childress wrote in a letter dated Monday. “But when, as now, I am no longer able to be fully engaged in any commitment I have made, it becomes time for me to step down. I have reached that point in my ability to continue to serve the NRA. As such, I must resign.”

But Childress, along with former NRA President Oliver North, previously raised concerns about the amount of money the NRA was spending on outside lawyer William Brewer and his firm Brewer Attorneys & Counselors, according to documents obtained by CNN.

When North raised concerns about the NRA’s spending, he was effectively ousted as the group’s president. NRA Chief Executive Wayne LaPierre accused North of trying to stage a coup, which North denied, and the NRA later sued North.

The NRA has denied that any of its payments to Brewer Attorneys are improper.

Childress did not cite the financial controversy in his resignation letter.

The former NASCAR driver is the fifth member of the NRA board to resign in recent weeks amid the controversy over NRA spending and the forced resignation of North. Last week, Julie Golob, a professional sport shooter, announced that she will not be finishing her full three-year term as an NRA board director, and three NRA members from the more than 70-member board resigned after raising concerns about reports of lavish spending and mismanagement by LaPierre, The Washington Post reported.

“We accept the resignation of Mr. Childress, and appreciate his many years of service to the NRA,” NRA President Carolyn Meadows said. “We wish him all of the best in his business endeavors and appreciate his desire to focus on those interests at this time. Of course, we are pleased to see that Mr. Childress will continue to support the organization and the constitutional freedoms in which it believes.”

A former racecar driver, Childress founded the NASCAR team Richard Childress Racing in 1969. The North Carolina-based team has since grown to be one of the largest NASCAR organizations, with championships won by racer Dale Earnhardt. Childress was inducted into the NASCAR hall of fame in 2017.

His departure from the NRA’s board comes as the organization has been roiled by turmoil among its leadership in recent weeks, as well as investigations into its finances.

Its top lobbyist, Christopher Cox, resigned in June after NRA leadership accused him of participating in an attempt to overthrow LaPierre — a charge Cox denied to The New York Times.

Jennifer Baker exited her role in July as the director of public affairs for the NRA lobbying arm.

The NRA has also been locked in a legal battle with its former longtime advertising partner Ackerman McQueen, and shut down production in June of its online streaming network, NRATV, which was operated by Ackerman.

The New York attorney general and Washington, DC, attorney general have opened investigations into the NRA and its foundation finances.