SAN FRANCISCO — John Mara offered up a full-throated defense of Roger Goodell and the embattled NFL commissioner’s handling of Deflategate on Wednesday at the NFL’s spring owners meetings.

In an exclusive interview with The Post, the Giants’ co-owner, one of the league’s most powerful establishment voices, stood up for the punishment of the Patriots and said he expects Tom Brady’s four-game suspension will stand even after an appeal.

“I believe [Patriots owner Bob Kraft] ultimately accepted the penalties because he knew he didn’t have anywhere to go” with an appeal or a potential lawsuit, Mara said as he departed on the final day of the meetings.

Kraft announced Tuesday he was standing down in the face of a $1 million fine and the loss of a first-round pick in 2016 and a fourth-rounder in 2017 for the Patriots being repeat offenders after a league investigation found team employees most likely conspired with Brady to doctor footballs.

Kraft claimed he reluctantly threw in the towel in the spirit of league camaraderie, but there was instant speculation he did so because Goodell — worried about a lawsuit from the NFL Players Association and Brady — had secretly agreed to reciprocate by reducing Brady’s suspension.

But Mara, who is on the NFL’s competition committee and in close contact with Goodell, told The Post that a quid pro quo on Brady’s punishment “doesn’t exist.”

Goodell, speaking to reporters Wednesday at the end of the meetings, was asked if Kraft’s decision would affect his handling of Brady’s appeal.

“No,” Goodell said flatly.

Mara added he would be surprised if the four games were reduced unless Brady — who was uncooperative with league investigator Ted Wells — produced new information in his appeal to Goodell.

Goodell said Wednesday the only thing that will help Brady is for him to cooperate in the appeal that, by NFL rule, must be held by next week. Brady refused to let the league look at his text messages or emails in the initial investigation.

“I look forward to hearing directly from Tom,” Goodell said. “If there is new information or there’s information in helping us get this right, I want to hear directly from Tom on that.”

Goodell also refuted media reports the Patriots only suspended the two Defltategate employees — locker-room attendant James McNally and equipment assistant John Jastremski — on the orders of the NFL.

Asked if that happened, Goodell said: “No.”

Mara agreed with the Patriots and other critics of Wells that the nearly three-month probe and 243-page report “wasn’t perfect,” but said Goodell and the league have no reason to apologize.

“I’m sure everybody believes there were certain things that maybe could have been done better, but overall, the league did what it was supposed to do,” Mara told The Post. “There was a situation brought to its attention, it has an obligation to investigate it and come up with findings, and the commissioner has the obligation to impose discipline if he thinks it’s necessary. That’s the way it unfolded, and so now we’re moving on.”

Mara wasn’t the first owner to stand up for Goodell since the Deflategate punishment came down, but the Big Blue boss’ comments certainly were the most vocal and detailed defense of the commissioner.

Mara said Goodell has “the overwhelming support of most of the owners” and scoffed at anyone who thinks Goodell’s job is in jeopardy — especially as a result of Deflategate.

“[Goodell is] expected to make very tough decisions,” Mara said. “Unfortunately, we’ve had a lot of cases in recent years where he’s been put on the spot, but that’s the job he was hired to do. And I think most of believe that he’s doing a good job.”

Mara also strongly defended Goodell’s right as commissioner to serve as judge, jury and executioner in disciplinary cases. The NFLPA ceded that power to Goodell in the 2011 labor battle, and Mara made it clear the owners won’t give it back without a fight.

“Having the final say-so is why you have a commissioner,” Mara said. “That’s what we bargained for, and there you have it.”