Mayors from more than 250 US cities have voted to transition to 100 per cent renewable energy in the next two decades, in a repudiation of the environmental policies of President Donald Trump.

The mayors voted on nine different energy resolutions at the United States Conference of Mayors, the 85th such gathering of leaders from more than 1,400 cities.

A key Conference resolution pledged support for “establishing a community-wide target of powering communities with 100 percent clean, renewable energy by 2035,” as a means of meeting the targets set by the Paris Agreement – a historic environmental pact from which Mr Trump recently removed the United States.

Just weeks before, mayors of more than 300 cities had pledged to honour the commitments of the climate accord, even if the Trump administration wouldn’t.

At the conference on Monday, mayors also voted ask Congress and the Trump administrative for risk management programmes to combat the effects of climate change, such as flooding from sea level rise. They also pledged to support more investment in wind energy from all levels of government.

"We are showing the world that cities and mayors can and will lead the transition away from fossil fuels to 100 percent clean, renewable energy," Columbia, South Carolina, Mayor Steve Benjamin, a co-sponsor of the resolution, said in a statement.

Paris climate talks in pictures Show all 12 1 /12 Paris climate talks in pictures Paris climate talks in pictures A man is covered with a multi-coloured banner with the message, "Climate" as environmentalists attend a demonstration near the Eiffel Tower in Paris, France, during the World Climate Change Conference 2015 (COP21) that meets in Le Bourget, December 12, 2015 Reuters Paris climate talks in pictures French President Francois Hollande (C) and French Foreign Minister Laurent Fabius (R) applaud after a statement at the COP21 Climate Conference in Le Bourget, north of Paris, on December 12, 2015. The years-long quest for a universal pact to avert catastrophic climate change neared the finish line today with conference host France announcing that the final draft had been completed in the early hours of the morning. Getty Paris climate talks in pictures US Secretary of State John Kerry (C) speaks with China's Special Representative on Climate Change Xie Zhenhua (R) and officials at the COP21 Climate Conference in Le Bourget, north of Paris, on December 12, 2015. The years-long quest for a universal pact to avert catastrophic climate change neared the finish line today with conference host France announcing that the final draft had been completed in the early hours of the morning. Getty Paris climate talks in pictures Delegates and members of NGO's read and work on copies of 'The adoption of the Paris agreement' is pictured after the announcement of the final draft by French Foreign Affairs minister Laurent Fabius at the COP21 Climate Conference in Le Bourget, north of Paris, on December 12, 2015. The years-long quest for a universal pact to avert catastrophic climate change neared the finish line with conference host France announcing that the final draft had been completed in the early hours of the morning Getty Paris climate talks in pictures UN climate chief Christiana Figueres (C) speaks with French President Francois Hollande (L), United Nations Secretary General Ban Ki-moon (2ndL) and French Foreign Minister Laurent Fabius (R) after a statement at the COP21 Climate Conference in Le Bourget, north of Paris, on December 12, 2015. The years-long quest for a universal pact to avert catastrophic climate change neared the finish line today with conference host France announcing that the final draft had been completed in the early hours of the morning Getty Paris climate talks in pictures A Swiss Dominican priest poses with activists dressed as polar bears as activists gather for a demonstration to form a giant red line at the Avenue de la Grande armee boulevard in Paris on December 12, 2015, as a proposed 195-nation accord to curb emissions of the heat-trapping gases that threaten to wreak havoc on Earth's climate system is to be presented at the United Nations conference on climate change COP21 in Le Bourget, on the outskirts of Paris. Getty Paris climate talks in pictures Activists hold up a giant banner reading 'Climate justice' by association 'ourpowercampaign' during a demonstration near the Arc de Triomphe at the Avenue de la Grande armee boulevard in Paris on December 12, 2015, as a proposed 195-nation accord to curb emissions of the heat-trapping gases that threaten to wreak havoc on Earth's climate system is to be presented at the United Nations conference on climate change COP21 in Le Bourget, on the outskirts of Paris. Getty Paris climate talks in pictures Representatives of indigenous peoples demonstrate in Paris, France, as the World Climate Change Conference 2015 (COP21) continues at Le Bourget, December 12, 2015. Reuters Paris climate talks in pictures Environmentalists demonstrate near the Arc de Triomphe in Paris, France, as the World Climate Change Conference 2015 (COP21) continues at Le Bourget, December 12, 2015. Reuters Paris climate talks in pictures Environmentalists demonstrate near the Arc de Triomphe in Paris, France, as the World Climate Change Conference 2015 (COP21) continues at Le Bourget, December 12, 2015. Reuters Paris climate talks in pictures Activists form a giant red line during a demonstration on the Avenue de la Grande armee boulevard in Paris on December 12, 2015, as a proposed 195-nation accord to curb emissions of the heat-trapping gases that threaten to wreak havoc on Earth's climate system is to be presented at the United Nations conference on climate change COP21 in Le Bourget, on the outskirts of Paris ALAIN JOCARD/AFP/Getty Images Paris climate talks in pictures The slogan "No Plan B" is projected on the Eiffel Tower as part of the World Climate Change Conference 2015 (COP21) in Paris, France, December 11, 2015. Reuters

In fact, an underlying theme of the conference seemed to be mayors leading the way – on climate change, and on everything else.

“The families we represent cannot look to Washington for answers,” conference President and New Orleans Mayor Mitch Landrieu told the mayors in his address. He added: “We cannot simply resist and retreat, we must lead, and we must engage.”

Former New York city Mayor Michael Bloomberg echoed these comments, claiming the federal government had been “AWOL” on “nearly all the big issues”.

“As Washington has grown more dysfunctional, cities have grown more dynamic, and mayors have grown more powerful and important,” he said.

Mr Bloomberg announced on Monday he will donate more than $200m to cultivate inventive city policies over the next three years. The American Cities Initiative will provide grants for mayors who tackle issues like climate change, education and opioid abuse.

He urged the mayors gathered there to “accelerate cities’ progress to make up for Washington's inaction”.

Even before the conference, America’s mayors were already butting heads with the Trump administration – most notably on the issue of immigration.

More than 150 cities and counties across the country have refused to cooperate with federal immigration enforcement officers in recent months, declaring themselves “sanctuary cities” for undocumented immigrants.

Mr Trump, in one of his first acts as president, issued an executive order withholding federal funds from such sanctuary cities.

In April, a federal judge blocked the order from taking effect.

"First the Ninth Circuit rules against the ban & now it hits again on sanctuary cities-both ridiculous rulings,” the President fumed on Twitter. “See you in the Supreme Court!”

Mr Landrieu, whose own jurisdiction has declared itself a sanctuary city, urged his fellow mayors to stay strong.