Bernie Sanders stands at the fringe no more.

The quirky independent from Vermont, once seen as more likely to lead a protest than pass a law, was at center stage early Wednesday when the Senate approved a historic $3.5 trillion budget blueprint. If congressional Democrats can hold together – and that is no small “if” – Sanders will have been one of the key architects of the biggest expansion of America’s social safety net since FDR.

He sounds just a little surprised about that journey himself.

“Ideas that I talked about when I ran for president in 2016, five years ago, were considered radical, like ‘Medicare for All’ or boldly addressing climate change or making sure that children had quality, affordable child care or demanding that the wealthy and large corporations are paying their fair share of taxes,” Sanders told USA TODAY in an exclusive interview a few hours after the vote, hardly pausing for breath, unwilling to leave any priority unmentioned.

Now, he said, “those have really become mainstream.”

To be sure, the budget bill passed only by a narrow margin and along party lines, 50-49, and even some Democrats now question its cost. Republicans hammer it as reckless spending by an out-of-control government, and Sanders’ embrace may help reinforce their depiction of it as a leftists’ dream.

But approval of the bill was a crucial milestone in the effort to enact what would be the most consequential social legislation in decades.

Sanders’ role in bringing that all about is notable not only because he chairs the Senate Budget Committee. Through a 40-year political career and two credible presidential campaigns, in 2016 and 2020, he has been the loudest and most persistent voice in pulling the Democratic Party to the left.

Over the decades, he hasn’t changed his label – he was calling himself a democratic Socialist before other ambitious politicians would have dared – or his open admiration for the governments of Scandinavia. But in the past year, since Democrats regained Senate control and seniority made him chair of one of Capitol Hill’s most powerful panels, he has adjusted some of his strategy and tactics.

“When you’re outside, running for office, that’s one thing,” he said. “When you’re a chairman of a committee in the Senate, where you have the members in the Democratic caucus, obviously, you know, your role changes.”

For instance, he declined to take a shot at West Virginia Sen. Joe Manchin or Arizona Sen. Kyrsten Sinema, Democrats who have called the budget price tag too high. That guarantees a conflict with progressives, especially in the House of Representatives, who complain that $3.5 trillion is just barely enough.

Even Sanders originally proposed a budget bill of $6 trillion, but now he is careful not to draw any lines in the sand.

“People have got to appreciate we are not operating with a significant majority,” he said. “(Speaker) Nancy Pelosi has three or four votes in the House, zero votes to spare in the Senate. So we are operating with the thinnest possible majority, and it’s going to require an enormous amount of work to bring people together who have different points of view.”

The budget plan is breathtaking in its scope. It calls for tuition-freepre-kindergarten and community college, paid family leave and child tax credits, and expanded Medicare benefits for seniors. Provisions would encourage clean energy and address climate change. With Republican opposition expected to be solid, Democrats’ task of first drafting the massive bill and then passing it will be daunting.

Sanders suggested he could play a part in persuading restive progressives, a group with whom he is familiar, to make the deals necessary to get the bill passed. “I am absolutely confident that while we fight to get as strong a package as we can, at the end of the day I think all of us will recognize that we are in the process of bringing forth transformative legislation,” he said.

Poised to celebrate his 80th birthday next month, he has from the start been the opposite of a cautious, blow-dried politician. He often doesn’t seem to have bothered even combing the gray hair that forms a messy halo around his head. He has been famously parodied by comedian Larry David on NBC’s “Saturday Night Live,” and even the colorful mittens he wore to President Joe Biden’s inauguration in January went viral – the gift from a Vermont teacher who wanted to cheer him up after he lost the presidential nomination to Hillary Clinton in 2016.

In an interview with USA TODAY’s Capital Download after that defeat, Sanders’ big ambitions were unvanquished. Asked if it was conceivable he would run for president again, he replied, “You know, it’s conceivable that I may fly to the moon.” The reporter demurred, “With all respect, it’s not conceivable that you may fly to the moon.”

“If Elon Musk called me, I could go to Mars!” he replied. “People don’t think big enough!”

Last week, SpaceX’s Starship officially became the world’s tallest rocket, on its way to becoming the craft that Elon Musk’s company hopes will carry humans to the moon, Mars and beyond.

And on Wednesday, Bernie Sanders was center stage on the Senate floor.