Randy Bernard stepped down as CEO of IndyCar on Sunday, bringing an end to a three-year reign that was disrupted this season by several attempts by team owners to have him ousted as head of the series.

The decision was announced following an executive session conducted by teleconference Sunday by the 11-member Indianapolis Motor Speedway board of directors.

Jeff Belskus, the president of IMS and president and CEO of Hulman & Co., will step in as interim CEO of the IndyCar Series. Bernard, who has two years remaining on the contract he signed when he joined IndyCar in 2010, will stay on in an advisory position.

The decision was immediately criticized by Roger Penske, the most powerful owner in open-wheel racing.

"I'm very disappointed in this decision; the board continues to show poor judgment. There is no future plan," Penske said. "The series had momentum. New cars, new engines and new race formats, all brought about by Randy.

"No business can run with a senior management change every two years."

Both the IndyCar Series and the Indianapolis Motor Speedway are owned by the Hulman-George family, which holds four spots on the 11-member IMS board and four spots on the 10-member Hulman & Co. board.

The decision for Bernard to step down was made by the IMS board, which felt a "mutual separation" was the only way to stop speculation over his job security.

Belskus, in a telephone interview Sunday night with The Associated Press during the final portion of the board meeting, gave few details about the split.

"Both parties agree that it's time to move forward separately, it's an amicable separation and Randy is going to stay on in an advisory capacity," Belskus said.

But IndyCar is coming off arguably its best season in series history. Bernard introduced the first new car in nine years this season, and the on-track product was perhaps the best in auto racing.

IndyCar had eight different winners, its first American champion since 2006 in Ryan Hunter-Reay, and Chevrolet won the engine manufacturer title in its return to the series after a six-year absence. Pressed how it was in IndyCar's "best interest" to part with a CEO who brought such positives to the series and was popular with fans, Belskus gave no answer.

"I'm not going to comment," he said.

It's been that kind of a month for IndyCar, which has been plagued by rumors of owner-led coups against Bernard all season. It reached a fevered pitch in the last month as series founder Tony George attempted to reclaim control with an offer to purchase the series from Hulman & Co.

It's long been believed that George, who was stripped of power in 2009 by his mother and three sisters, has been leading the charge to oust Bernard, who was hired in 2010 to re-energize the series.

Hulman & Co. has insisted George's offer was never entertained and IndyCar is not for sale. But George stepped down from the board nine days ago, citing a conflict of interest in holding a seat while trying to purchase the series.

It did nothing to quiet the uncertainty surrounding Bernard, who has worked for more than a year amid uncertain job security because he could never secure any sort of public support from the board of directors or the Hulman-George family.

The speculation was suffocating last week, and Bernard and an IMS spokesman both denied a report Friday that Bernard had been fired. It led driver Graham Rahal, one of the most recognizable names in the series, to plead for some sanity Friday afternoon.

"Come on people either keep Randy or fire him but this is foolish and embarrassing for this sport," he posted on Twitter.

After two days of silence and Bernard in apparent limbo, the IMS board called an emergency teleconference Sunday to figure out a solution.

In a statement, Bernard specifically thanked Josie George, who brought him to IndyCar and said the series is "better poised for success than it has been in many years.

"I have developed a passion for the sport of IndyCar," he said in the statement. "As IndyCar fans, we need to unify behind the sport in order to move it to the next level, and I look forward to providing input and being part of that unified voice along the way."

It's not clear what's next for the troubled series.

"Well, I have been named interim CEO," Belskus told AP. "We're going to conduct a search. We haven't established a specific timeline for a permanent replacement. It's all part of a planning process that we'll address."

It didn't sound very promising to Zak Brown, founder and CEO of the motorsports marketing agency Just Marketing International, and the man many believed would run IndyCar under George's offer to buy the series. Brown has said he has no interest in running IndyCar.

"It all appears a bit strange and kneejerk to me," Brown said Sunday night. "I don't understand why Jeff Belskus hasn't communicated a longer-term plan. Unless there isn't one, which as CEO, I hope he has. The industry needs to know the plan."

So do the weary fans, who seemed overwhelmingly in support of Bernard and had been threatening for weeks via social media to turn their backs on the series for good if George regained control or Bernard was let go.

Belskus said he's unsure what reaction will be to Bernard's departure.

"It is change and we recognize that different people deal with change differently, and with people differently," he said.

Engaging and energetic, Bernard had bold ideas in his attempt to revitalize a racing series clinging for relevancy outside of the Indianapolis 500.

But Bernard was stymied by a combination of his own missteps, the same old drama and dysfunction that weakened open-wheel racing and allowed NASCAR to surpass it as the top racing series in America, and the massive mess left behind by George.

And even if Bernard had been flawless at his job, it likely still wouldn't have been enough.

George wanted his series back and wanted Bernard gone, and even if he couldn't make it happen, Bernard couldn't find enough allies in a paddock that ran through CEO's at a comical rate before George formed IndyCar.

Plus, it's been a rough 13 months for Bernard, whose tenure was rocked by the death of two-time Indianapolis 500 winner Dan Wheldon in the 2011 season finale.

Wheldon was only in the race as part of a $5 million promotion Bernard had devised as a means to close the season with a bang and build momentum for what was expected to be a breakthrough 2012 for IndyCar. Wheldon's death paralyzed IndyCar for months, and took a heavy emotional toll on Bernard, who after 15 years with The Professional Bull Riders was unaccustomed to the inherent dangers of auto racing.

And Bernard, who maybe was naive to just how political the IndyCar paddock can be, found himself putting out fire after fire every time he turned around this year. Team owners appeared to begin turning on him following a meeting at Long Beach in April in which they complained about the cost of replacement parts and a series ruling in the "Turbogate" scandal that allowed Honda to make a change to its engine.

Rumors swirled during the entire buildup to the Indianapolis 500 of an owner-led attempt to have him fired. Bernard confirmed the plot in an ill-timed tweet two days after the race, removing all focus from what many believed had been one of the most exciting 500s in years.

Although talk of Bernard losing his job quieted after the tweet, the board of directors — which failed to offer him any support during the attacks following Wheldon's death — still remained silent about his job security.

By August, there was talk of the George-led effort to buy the series.

That his job status was even in question was puzzling to outsiders, who point to years of instability and dysfunction in American open-wheel racing. Bernard had been brought in specifically tasked with cleaning up 14 years of disaster left behind after George had hemorrhaged family money for years on IndyCar.

Bernard was supposed to stop the bleeding, and immediately slashed the budget. He worked toward dramatically cutting losses that reportedly averaged high eight figures under George's watch to mid-to-low seven figures for Bernard.

More important, he dramatically improved the product.

Bernard this year introduced the new car and brought in multiple engine manufacturers. He cleaned up the grid last year with harsh league scrutiny on Milka Duno, who had sponsorship to get a ride but was not skilled enough to be on the track, and that in part contributed to parity this season throughout the field.

Bernard also removed Brian Barnhart from his longtime role as head of race control following a controversial 2011 season in which it was clear Barnhart had lost the trust of the paddock. He also developed the "Road to Indy" ladder system, a development program meant to keep young drivers in IndyCar.

This season, Bernard was able to save Milwaukee from dropping off the IndyCar schedule — albeit in a sweetheart deal for first-time promoter Michael Andretti — but Bernard also got Andretti to step in and rescue the endangered Labor Day weekend event at Baltimore. He also brought IndyCar back to Fontana, Calif., this season for the first time since 2005, and announced last month that IndyCar will race in 2013 at Pocono after a 23-year absence.

Bernard announced the return of the "The Triple Crown" promotion, an IndyCar tradition last done in 1989, the last time the series visited Pocono. He's also been in talks with Phoenix and Michigan, two other traditional IndyCar tracks, about returning to the series for the 2014 season.

Although he received mixed reviews for his 2013 schedule announced earlier this month, few understood his reasoning for creating doubleheaders or a long summer-stretch of racing. Saddled with a tough television package he inherited from George, Bernard strung together six consecutive weeks of racing through the summer to get five dates on ABC, including a prime-time Saturday night event at Texas Motor Speedway.

And because IndyCar has so little shoulder programming and cable partner NBC Sports does not often air qualifying live, Bernard viewed doubleheaders as a way to get the series on television more often.

Alas, none of his gains were ever lauded the way his missteps were jeered.

The cancellation of an August race in China was a reported $7 million hit to his budget — one of the reasons speculated he fell out of favor with the board. And Bernard's desire for engine competition led him to ignore all red flags and welcome Lotus into to the series. The manufacturer was an embarrassing disaster from start to finish.