John Mellencamp before President Obama’s arrival at a campaign stop in Dubuque, Iowa, in 2012. (Nikki Kahn/The Washington Post)

It was 1976. John Mellencamp, guitar picker from Indiana, was just 25. Though still baby-faced, he had lived through quite a bit. He survived spina bifida as a child at a time when many did not. He had fronted a soul band at 14. He became a dad at 19.

And now, looking at the cover of his hard-fought-for debut album, he was mad as hell. His manager said the record wouldn’t be credited to “John Mellencamp,” but to “Johnny Cougar.” Because “Mellencamp” was too much of a mouthful, right? And Mellencamp was from the heartland, right? And — aren’t there cougars in Indiana?

Surprise.

“I was totally unaware of it until it showed up on the album jacket,” Mellencamp later said of the record, “The Chestnut Street Incident.” “When I objected to it, he said, ‘Well, either you’re going to go for it, or we’re not going to put the record out.’ So that was what I had to do … but I thought the name was pretty silly.”

Almost 40 years later, the artist formerly known as Puma concolor has penned a letter to the editor of the Indy Star decrying Indiana’s new Religious Freedom Restoration Act (RFRA), which opponents say discriminates against gays. And, though he ditched the stage name years ago, his transition from “Cougar” to commentator is complete.

“It is with a very heavy heart that I’ve watched the divisiveness that has occurred over our state government’s actions,” Mellencamp, 63, wrote in a letter also posted to his Web site. “I am not questioning the sincerity of those who believe they have acted in the interests of religious freedom, but I am resolutely stating my opposition to this misnamed and ill-conceived law. It is discriminatory, hurtful, and a stain on Indiana’s national reputation.” (Mellencamp has not commented on the update to RFRA just signed by Indiana’s Republican governor, Mike Pence.)

[Indiana pizza shop won’t cater gay wedding, gets over $50K from supporters]

[Gov. Pence signs revised Indiana religious freedom bill into law]

It’s no secret that, though he lives in a red state, Mellencamp’s blood runs blue. He helped organize Farm Aid. He has written songs criticizing Ronald Reagan and George W. Bush. He told John McCain to stop campaigning with the song “Pink Houses” — which Mellencamp played at President Obama’s inauguration in 2009. As he told Salon in 2013: “I’m as left wing as you can get.”

But, in the world of heartland rock — pop music with a country edge often about working-class themes — Mellencamp has often been overshadowed by a certain other blue-collar rocker with liberal politics from a less-than-glamorous corner of America.

“The way Mr. Mellencamp’s albums have changed tone suggests that, like many other 1980’s rockers, he’s kept an ear on Bruce Springsteen,” New York Times music critic Jon Pareles wrote in 1987 in a piece called “Heartland Rock: Bruce’s Children” — an excruciating title for anyone trying to compete with the Boss. Pareles took it as gospel that Mellencamp was merely following the trail Springsteen blazed.

“Mr. Springsteen established heartland rock’s main topics — unemployment, small-town decline, disillusionment, limited opportunity, bitter nostalgia,” he wrote. “And with the overwhelming success of his 1984 album ‘Born in the U.S.A.,’ which sold 11.5 million copies in the United States alone, the style became a full-fledged movement, one that Mr. Mellencamp joined in 1985 with ‘Scarecrow.’ ”

But “Scarecrow” — though a huge hit with singles such as “Lonely Ol’ Night” and “R.O.C.K. in the U.S.A.” — couldn’t quite compete with “Born in the U.S.A.” More than 15 years after its release, it had sold a mere 5 million.

In a 1986 interview with Rolling Stone, Mellencamp sort of admitted he owed Springsteen a debt.

“I didn’t even think about the Springsteen comparison,” he said. “What Springsteen does is a marathon. What we do is a sprint.” Mellencamp even honored the Boss at the Kennedy Center in 2009 — when, it might be noted, Springsteen was the one actually getting the Kennedy Center Honor.

Of course, there is room for more than one blue-collar rocker in the pantheon of rock ‘n’ roll — just ask John Fogerty, Tom Petty and even Melissa Etheridge. But in speaking out against RFRA, Mellencamp seems to have found his Boss moment.

As one commenter on Mellencamp’s Facebook page put it: “Love you…your music…and this beautiful commentary. Puts it all in perspective.”

Getting praise from fans, though, is easy. What shows Mellencamp has really made his bones is conservative ire.

“You are an idiot,” another commenter wrote. “Shut up. Nobody cares what Hollywood or singers think about this. Get the facts straight if you plan to talk about subjects that matter. At least do that much before you talk about something you are clearly clueless about. Sad!!!!”