SAN FRANCISCO (CBS SF) — A landmark measure by the Obama administration to curb carbon dioxide pollution from power plants is expected to be rolled back by President Donald Trump, prompting a group of West Coast governors and mayors to pen a joint statement in opposition.

The U.S. Environmental Protection Agency’s Clean Power Plan made history in 2015 by setting the first national limit on the amount of carbon dioxide pollution that can be produced by power plants.

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In anticipation of an executive order from the president, governors representing the states of Washington, Oregon and California have banded together with mayors from major West Coast cities to reaffirm their support of the Clean Power Plan.

The West Coast mayors and governors issued a joint letter stating that regardless of what the Trump administration decides to do, they will continue to promote clean energy.

“We speak as a region of over 50 million people with a combined GDP of $2.8 trillion. There is no question that to act on climate is to act in our best economic interests. Through expanded climate policies, we have grown jobs and expanded our economies while cleaning our air,” said the governors of California, Oregon and Washington as well as the mayors of Seattle, Portland, San Francisco, Oakland and Los Angeles.

A spokeswoman for Washington Gov. Jay Inslee said her office has been informed that a directive related to the Clean Power Plan could come from the president as early as Friday, but she said that the delayed vote on the health care bill could push things back.

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The letter stated, “We will honor our commitments to our communities to do what’s right to keep our residents safe, secure, healthy and prosperous as we accelerate our clean energy economy and put the interest of our people before those of big polluters. We will continue to invest in clean energy that creates local jobs and keeps utility bills low, and we will electrify transportation to provide convenient, safe, and affordable ways to get around our cities, and make our neighborhoods healthy and vibrant.”

They urged cities, states and businesses from around the country to join them to cut carbon emissions where they live and to help “reverse the damaging impacts to our communities of unfettered pollution.”

Following the passage of the Clean Power Plan in 2015, the American Coal Council said in a statement that, “It will destroy good jobs, raise electricity prices, disproportionately affect low-income households, and damage America’s ability to compete internationally. We support continued efforts to counter this misguided regulation.”

The White House has also proposed cutting the EPA’s budget by 31 percent, more than any other agency.

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By Hannah Albarazi – Follow her on Twitter: @hannahalbarazi.