WASHINGTON • From the earliest days of his presidential campaign, Mr Joe Biden has been viewed with deep scepticism by progressive climate advocates.

He had declined to fully endorse the Green New Deal. He opposed a total fracking ban. Young activists were scathing in their criticism of him, and he was at times openly dismissive of their concerns.

Now, with less than four months before election day in the US, Mr Biden is moving urgently to unite and energise the Democratic Party around his candidacy, aware of the need to engage younger, more liberal voters - and to ensure that they turn out on Nov 3.

On climate issues, there are signs that Mr Biden's allies and some of the party's leading progressives have quietly started to forge new common ground.

In recent weeks, supporters of Mr Biden and of Senator Bernie Sanders of Vermont, his chief rival in the Democratic presidential primary race, have met privately over Zoom, part of several joint task forces that the two contenders established to generate policy recommendations on core domestic priorities and to facilitate party unity.

After two months of those conversations, task force members representing both camps say they have finalised ambitious, near-term climate targets they hope Mr Biden will incorporate in his platform.

Those targets, according to three people familiar with the task force's decisions, include committing to seeing the US' electricity sector powered fully by renewable energy by 2035 and a rapid transition to energy-efficient buildings.

They also seek a "day one" promise to begin developing new vehicle efficiency standards - and include labour unions in the discussions - to replace and improve upon the Obama-administration measures that President Donald Trump has weakened.

The group, which convened amid the economic collapse during the coronavirus pandemic and protests against racism and police brutality, was especially attuned to linking the climate crisis to jobs as well as to the struggle to help low-income communities that already face outsized health consequences from pollution, task force members said.

Mr Biden, the former US vice-president, last year proposed a US$1.7 trillion (S$2.4 trillion) plan aimed at achieving 100 per cent clean energy and eliminating the US' net carbon emissions by 2050.

In recent weeks, he has made a number of overtures to climate activists. He has increasingly linked environmental issues to racial justice, and promised to send Congress "a transformational plan for a clean energy revolution" in his first 100 days in office, if he is elected.

From the start of his presidential run, Mr Biden has walked a fine line between championing climate change action and trying to engage union members who still rely on jobs in fossil fuel industries, as well as moderate Republicans who might dislike Mr Trump yet oppose aggressive action on curbing greenhouse gases.

The future of natural gas, and its implications for jobs, is a major fault line that separates the Obama-era climate policy leaders from the new generation of activists.

Natural gas produces about half the emissions of coal. Much of the Obama administration's energy strategy centred on promoting it as a "bridge fuel" to wean the country off dirtier fossil fuels until the price of renewables dropped.

Now, the average cost of new wind or solar power is less than the costs of running most coal-fired plants, an analysis last year by two energy research groups showed.

But in places like Pennsylvania, a state Mr Trump won by less than 1 percentage point in 2016, the natural gas sector is responsible for thousands of high-paying union jobs.

So when Mr Biden, during a pointed exchange with Mr Sanders on the debate stage in March, declared "no new fracking", some allies were alarmed, including former Pennsylvania governor Edward Rendell, who said he called the campaign to voice his concern.

Mr Biden had proposed ending new fracking leases on federal lands, but not a national ban, something his campaign clarified.

Mr Andrew Baumann, a Democratic strategist and pollster, said there were limits to how far Mr Biden could push on climate matters without encountering political risk - but that he was "pretty far away from that".

"It is possible to go too far," he said. "But the amount that is there to go bolder before you reach that level is really a lot bigger than people think."

NYTIMES