Liberal activists have opened a new front in their battle to push Joseph R. Biden Jr. to the left on climate change: a campaign to pressure the Democratic presidential nominee to reject advisers with any ties to fossil fuel companies.

The targets include former Energy Secretary Ernest Moniz, former Interior Secretary Ken Salazar and others who served in the Obama administration.

Last week more than 60 deep-pocketed donors asked Mr. Biden to commit to a moratorium on all new coal, oil and natural gas development — and to select advisers who are “free from fossil fuel influence.” The group, which includes Kathy Washienko, a clean-energy investor in Seattle; Robin Chase, a co-founder and former chief executive of Zipcar; and Adelaide Park Gomer, the president of the Park Foundation philanthropic group and a longtime anti-fracking activist, implored Mr. Biden to “choose new, bolder leadership” than those with whom he worked under President Barack Obama.

“This incumbency of old ideas (like ‘all of the above’ energy policy) must end,” the donors wrote.

The effort comes just days after Mr. Biden denounced President Trump as a “climate arsonist” and made the case that Americans suffering from wildfires, floods and hurricanes could not afford four more years of a climate-change denier in the White House. Even many of Mr. Biden’s persistent critics on the left described it as the most aggressive and detailed policy speech on climate change ever given by a presidential candidate.

Guest post from The New York Times