Presumptive Green Party candidate for U.S. President Jill Stein has reiterated her offer for Bernie Sanders to head that party’s ticket instead, where—unlike in the Democratic party—she says he’d be able to continue to “build a political movement.”

Stein’s new comments to the Guardian US come as the Vermont senator has signaled he may soon offer an endorsement of rival Hillary Clinton.

Stein, who also ran for president on the Green Party ticket in 2012, told the Guardian US: “If he saw that you can’t have a revolutionary campaign in a counter-revolutionary party, he’d be welcomed to the Green party. He could lead the ticket and build a political movement,” she said.

It’s a suggestion she’s made already this campaign season.

After the New York primary, which took place April 16, Stein wrote to Sanders: “At a time when the American electorate is rejecting politics as usual in vast numbers, I invite you to join me in pushing the boundaries of that system to a place where revolution can truly take root.”

“In this hour of unprecedented crisis—with human rights, civilization, and life on the planet teetering on the brink—can we explore an historic collaboration to keep building the revolution beyond the reach of corporate party clutches, where the movement can take root and flourish, in the 2016 election and beyond?” she wrote.

Sanders, speaking in May, didn’t fully rule out such a possibility. “If polls show that you could beat Donald Trump as a Green Party candidate, would you run?” a local reporterasked him before a rally in Santa Monica, California. Sanders responding by saying, “Right now our goal [..] is to win the Democratic nomination.”

Stein told the Guardian that she believes many Sanders backers—who were drawn to the ideas of his “political revolution”—won’t simply switch their support to Democratic rival Clinton. “For many people,” she told the Wall Street Journal, “we’ve been Plan B for when Bernie got shut down by the Democrats.” And, she told the Guardian, in her view, “It’s a mistake to think the lesser of two evils will fix things.”

“If [Sanders] continues to declare his full faith in the Democratic party, it will leave many of his supporters very disappointed,” she said. “That political movement is going to go on—it isn’t going to bury itself in the graveyard alongside Hillary Clinton.”

Speaking to Democracy Now! last month, Stein said that “over the years, the [Democratic] party has allowed principled candidates to be seen and heard, but has, at the end of the day, sabotaged them in one way or the other, often through fear campaigns and smear campaigns, in the same way that Bernie is being called a spoiler now.”

According to Stein, “in many ways, the Democratic Party creates campaigns that fake left while it moves right and becomes more corporatist, more militarist, more imperialist. This is why we say it’s hard to have a revolutionary campaign inside of a counterrevolutionary party. That’s why we’re here as the Green Party to build a place where a revolutionary movement can truly grow with a political voice.”

Regarding a Sanders-Stein ticket, she told Democracy Now! she was unsure of how the rules worked, saying, “It would probably have to be taken to the Green Party convention,” which takes place August 4-7 in Houston.

Still, she said, “I would be very interested in having this discussion. I am not holding my breath that it’s going to happen. And I think it’s important that our campaign be plan B, if not for Senator Sanders, then for his supporters.”

Stein, a 66-year-old physician, has a platform that calls for a Power to the People Plan, which includes a Green New Deal, an improved Medicare-for-all national healthcare system, and the abolition of student debt.

A CNN/ORC poll released in June found that in a four-way matchup between Stein, Clinton, Republican presumptive nominee Donald Trump, and the Libertarian Party’s Gary Johnson, Stein would get 7 percent of the vote. For respondents still unsure how they would vote in a two-way matchup between Clinton and Trump, 12 percent said they’d back Stein if it were a four-way contest.