INDIANAPOLIS - IndyCar president of competition Derrick Walker took the fall Thursday for technical issues that have plagued the series this year and said he'll resign his position at the end of the season.

Walker will stay on for the final three races of the season, which ends Aug. 30 in Sonoma, California. Walker said in a statement that the timing is right to move on to other opportunities after 2 1/2 seasons on the job.

"I have appreciated the opportunity to work closely with the team owners, drivers and the team," Walker said.

IndyCar CEO Mark Miles said Walker's resignation surprised him, but that he understood the decision. He said Walker felt responsible for issues that have plagued the introduction of aero kits this year, and for the incidents that led to an 11th-hour change in qualifying rules for the Indianapolis 500.

Three cars went airborne in preparation for the 500, and an emergency rule change was made the morning of qualifying because IndyCar wasn't sure why the cars were lifting.

"We were talking about push rods and he pulled out a letter that said he decided at the end of the year, he was going to move on," Miles told The Associated Press. "Major issues, we look at at the end of the year. So it was not time for me for to evaluate that. But the year has not gone swimmingly, we've had things that were not planned, and he's a big enough guy to take responsibility for that. I think he was being hard on himself."

Miles also said he believed Walker felt he'd lost the support of the paddock.

"I think he felt at least a couple of influential team players — I'm not going to name level or people — but had turned on him and he was personally disappointed," Miles said. "And he's a sensitive guy. It's probably the toughest job in motorsports."

Walker helped IndyCar land Boston as a new race in 2016, helped introduce a road course race at Indianapolis Motor Speedway and changed the way race control is run. He was also in charge as the new body kits were introduced this year, and although they were rolled out amid great fan anticipation, the kits were brittle any contact left the racing surface littered with parts and pieces. A series of reinforcements were made right after the season-opening race, where a fan was struck in the head with a piece of debris that had flown over the grandstands.

Walker has been in involved in racing in more than 40 years, in several series, including team ownership.