The youth-led grassroots group Sunrise Movement was praised on Thursday when Beto O'Rourke signed the No Fossil Fuel Money pledge following a sustained campaign by the national organization.

O'Rourke announced he was on board with the pledge in an email to supporters and a video posted to social media.

"In accordance with the pledge, we returned any money we've received over $200 from any fossil fuel company executives," O'Rourke said. "We will not take any of that money going forward."

The Sunrise Movement applauded O'Rourke's decision and noted that its actions across the country through local chapters in cities and states across the country had forced the former congressman to sign the pledge.

"Sunrise leaders from Virginia to Iowa to Texas, concerned about the stranglehold of Big Oil money on American democracy, asked O'Rourke to take the No Fossil Fuel Money pledge," said Varshini Prakash, the group's co-founder. "We're grateful for their efforts and heartened that Beto responded by returning previous donations from fossil fuel executives and refusing future donations."

Some establishment Democratic leaders including Rep. Dianne Feinstein (D-Calif.) have criticized the Sunrise Movement for its tactics as it calls on elected officials to end their relationships with the fossil fuel industry, back a Green New Deal, and fight to end American dependence on carbon-emitting coal, oil, and gas, which have contributed to the warming of the planet.

The Sunrise Movement has occupied the offices Feinstein and other Democrats in recent months, and offered limited praise for O'Rourke this week when he released his climate action plan, saying it represented his retreat from an earlier stated goal of net-zero domestic carbon emissions by 2030. Nearly 150 members were arrested in December on Capitol Hill at a protest where they called for a Green New Deal.  

Supporters of the grassroots group argued on Thursday that its commitment to continued pressure is what made its demands impossible for O'Rourke and other candidates to ignore—making it more likely that Democrats will eventually nominate a candidate who owes nothing to fossil fuel donors and can regulate the industry while promoting renewable energy.

Supporters of the grassroots group argued on Thursday that its commitment to continued pressure is what made it impossible for O'Rourke and other candidates to ignore their demand. They also said sustained pressure will make it more likely Democrats will eventually nominate a candidate who owes nothing to fossil fuel donors and can regulate the industry while promoting renewable energy.

O'Rourke acknowledged that young Americans' increasingly urgent calls played a role in his decision to sign the pledge.

"I'm doing this in large part because I was asked to by students that I met at William and Mary University when we were in Virginia," said O'Rourke. "I want to say to those students, especially those at William and Mary who spent the time to talk with us, thank you for your advocacy and your leadership on this issue. I look forward to working with you going forward."

O'Rourke became the 12th candidate to sign the pledge, which has been promoted by both the Sunrise Movement and Oil Change USA. Those who have also promised to take no campaign contributions from fossil fuel giants include Sens. Bernie Sanders (I-Vt.), Elizabeth Warren (D-Mass.), and Kirsten Gillibrand (D-N.Y.).

Following O'Rourke's announcement, the Sunrise Movement called on the rest of the Democratic 2020 field to take the pledge or risk losing support from the 82 percent of Democrats who count a commitment to climate action among their top priorities for presidential candidates—especially younger voters.

"Any candidate who wants to be taken seriously by our generation needs to sign the pledge and back the Green New Deal," Prakash said.