President Trump is expected to sign an executive order Tuesday that would take the first steps to roll back Obama-era protections of small streams and wetlands, making good on his promise to curtail government regulations that he says impede business.

The order is expected to mandate that the Environmental Protection Agency and the Army Corps of Engineers review a rule redefining which "waters of the United States" receive protections under the Clean Water Act, according to a senior White House official who spoke to reporters anonymously. Under former President Barack Obama, the law was adjusted to include smaller creeks and wetlands. Mr. Trump's expected reversal of that decision drew swift backlash from environmental advocacy groups.

“President Trump's order turns the mission of the Environmental Protection Agency on its head: Instead of protecting the drinking water sources for 1 in 3 Americans, he is telling the EPA to stop protecting these waters from polluters. It defies common sense, sound science and the will of the American people,” John Rumpler, senior attorney for Environment America said in a statement provided to The Christian Science Monitor.

Trump rallied against what he saw as excessive regulation and the overreach of the federal government during his campaign for the presidency. His criticism included the water rule, which farmers and landowners have also complained places an undue burden on their business operations.

Meanwhile, Democrats and environmentalists argue that the measure can ensure millions of Americans have access to clean drinking water, and they hope it will clarify confusion surrounding US Supreme Court rulings on waterway regulations. The agencies finalized the rule in 2015, but it was blocked by a federal appeals court and faces further legal challenges.

Conservatives praised that judgment, arguing that the effort to expand regulations beyond navigable waters to encompass adjacent ones such as seasonal streams and ditches gave the EPA too much authority over local land use.

The Supreme Court agreed last month to resolve a dispute as to whether a federal or district court should handle issues of water regulations going forward. The impending order also instructs the agencies to ask the attorney general to suspend litigation surrounding the rule while conducting the review.

The order comes as the EPA faces an uncertain future under the Trump administration. The president’s proposed budget unveiled a potential 24 percent reduction in the agency’s budget Monday.

And the agency’s new leader, Scott Pruitt, hasn’t quelled any anxieties of those urging officials to fight climate change and pollution. He has said that calls to do away with the agency are “justified” and spoken of dismantling Mr. Obama’s Clean Power Plan.

While the EPA has been viewed through a heightened partisan lens in recent years, some have noted that Trump’s administration seems to take the agency further to the right than former President George W. Bush’s ever did.

“If you have a scale of 1 to 100, you had the Bush EPA that seemed generally fairly balanced.… You had the sense in general that it was a responsible organization,” Rep. Don Beyer (D) of Virginia, told The Christian Science Monitor. “Then Obama came in and ratcheted it up to an 80 or 85 and tried to be much more aggressive about dealing with things.”

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“I was much more comfortable with the Bush EPA than I am with a ... Scott Pruitt EPA,” she added.

This report contains material from the Associated Press and Reuters.