WASHINGTON (Reuters) - Democratic presidential candidate Joe Biden won the support of two of his party’s most prominent climate change campaigners, including former presidential candidate Al Gore, on Wednesday.

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The endorsements of Gore and Washington state Governor Jay Inslee came as Biden seeks credibility with liberal voters he is courting as he tries to unify Democrats ahead of the Nov. 3 election against Republican President Donald Trump.

“I am proud to endorse my friend Joe Biden for President,” said Gore on Twitter.

Gore, who was the U.S. vice president from 1993 to 2001, became known for his advocacy on climate change after he lost a bitterly contested close-call election for president against George W. Bush in 2000. He was expected to join Biden at an Earth Day campaign event to be held online on Wednesday.

Inslee, meanwhile, had centered his one-time 2020 presidential bid on taking aggressive action to combat climate change.

During his year-long presidential campaign Biden has been regularly confronted on the campaign trail by activists who thought his climate policies were too centrist. Biden sometimes told those people to vote for someone else.

The former vice president does not support a ban on fracking, which contributes to climate change but is a source of jobs for members of Democratic-aligned labor unions. And his goal to significantly curb carbon emissions by 2050 is viewed by some activists as a too-distant goal.

Inslee said that Biden had supported the creation of clean energy jobs during the economic recovery from the 2008-2009 financial crisis as part of the Obama administration.

“As a result of this, you have helped create 3.3 million jobs in clean energy - jobs that didn’t exist before,” Inslee said as he announced his endorsement during an episode of Biden’s podcast.

Biden said as the country contends with the novel coronavirus outbreak and resulting economic downturn, jobs in clean energy could again drive economic recovery.

Green jobs “can be the very thing that helps us get through this existential threat to our economy,” Biden said on the podcast.

Biden has called for spending $1.3 trillion over a decade on electric-car charging stations, high-speed railroads, clean-energy research and other infrastructure that could limit the effects of climate change.

Democrats are eager to project unity heading into the race against Trump. Last week, Biden received a string of high-profile endorsements from Senator Bernie Sanders of Vermont, Senator Elizabeth Warren of Massachusetts and former President Barack Obama.