Former Vice President Al Gore on Sunday endorsed Vice President Kamala Harris for president, joining a chorus of Democrats supporting her bid to replace President Biden as the party’s presumptive nominee.

Gore, a prominent environmental activist, cited Harris’s past support for action addressing climate change action in making his endorsement.

“As a prosecutor, @KamalaHarris took on Big Oil companies – and won. As @VP, she cast the tie-breaking vote to pass the most significant investment in climate solutions in history, the Inflation Reduction Act,” Gore said in a statement on the social platform X. “That’s the kind of climate champion we need in the White House.”

“With so much at stake in this year’s election – from strengthening democracy in the US and abroad, to expanding opportunity for the American people, to accelerating climate action – I’m proud to endorse Kamala Harris for President,” he added.

Many Democratic officials have backed Harris, who faces no serious challenger to lead the ticket and who has already secured enough delegates’ support to win the nomination.

Former President Clinton and Secretary of State Clinton both endorsed Harris’s bid when Biden announced on July 21 he would no longer seek the nomination. Former President Obama and first lady Michelle Obama also endorsed Harris’s candidacy this past week.

Gore served as Clinton’s vice president. He ran for president in 2000 but lost to then-candidate George W. Bush in an historic election.