The Sunrise Movement signaled this week that it won’t surrender its environmental crusade despite Joe Biden becoming the presumptive Democratic presidential nominee. The climate activist group is now aiming to force the former vice president to adapt its platform during the general election.

The group originally endorsed Sen. Bernie Sanders for president and poured massive resources into supporting his campaign before he dropped out on Wednesday. Its leadership is now resorting to pressuring Biden under the threat of withheld financial contributions.

The Sunrise Movement’s demands of Biden, which came mere hours after Sanders’ announcement, show its support will be dependent on his outreach to liberal young people and the embrace of aggressive climate policies like the Green New Deal.

In a letter co-signed by numerous leading liberal activist groups, the Sunrise Movement wrote that Biden must do more to engage young voters.

“While you are now the presumptive Democratic nominee, it is clear that you were unable to win the votes of the vast majority of voters under 45 years old during the primary,” the letter stated.

“With young people poised to play a critical role deciding the next president, you need to have more young people enthusiastically supporting and campaigning with you to defeat Trump. This division must reconciled so we can unite the party to defeat Trump,” it continued.

Part of that unity must be centered around environmental issues and climate change, The Sunrise Movement argues. The letter wants Biden to “adopt the frameworks of the Green New Deal and make specific commitments around achieving a just transition to 100% Clean Energy by 2030.”

The letter also wants Biden to “prosecute fossil fuel executives,” a position Biden has supported in the past, saying he would “put them in jail.”

The Sunrise Movement and the other activist groups signing the letter are using money as leverage in an attempt to move Biden to the left. They pledged $100 million to support his campaign only if he agreed to an extensive wish list of policies including climate, gun control, Medicare for All, a wealth tax, and appointing leading liberal figures to his administration.

Finding common ground may be difficult, however. The Sunrise Movement has never been particularly fond of Biden, giving him substantially lower marks on its presidential scorecard than Sanders and its other preferred candidate, Sen. Elizabeth Warren.

And it attempted to stop Biden’s march to the nomination after he secured massive primary victories on Super Tuesday and the weeks after.

Aggressive posturing towards the party’s establishment has long been a hallmark of The Sunrise Movement. It has pressured Democratic leadership in the U.S. House to embrace The Green New Deal and called for the Democratic National Committee to hold a presidential debate last year focused solely on climate change.

Biden has extended an olive branch to environmental groups by stating the Green New Deal provides a “crucial framework” for meeting climate goals and he’s vowed to ban oil and natural gas production on public lands.

He’s also stated that he would pick a woman as his vice president, someone who could possibly reach out to The Sunrise Movement and other environmental activist groups.