By Rene Marsh CNN

WASHINGTON (CNN) -- President Donald Trump signed a measure Thursday that rolls back a last-minute Obama administration rule aimed at stopping the coal mining industry from dumping waste into nearby waterways.

It is the first of what is expected to be many environmental regulation rollbacks sent to his desk by Congress.

Both the House and Senate approved the measure through the little-used Congressional Review Act, which allows lawmakers to roll back any regulation the Obama administration instituted from June to his last day in office. Republicans have been using it to target regulations they regard as a burden on economic growth and businesses.

Trump's move Thursday may be just be the beginning of undoing some environmental protections. A source close to the administration tells CNN that soon after Scott Pruitt is sworn in as administrator of the Environmental Protection Agency, the President will take executive action directing Pruitt to make good on campaign promises related to climate change policy and regulations. This source says the timing for exactly when the President will act and how many executive orders there may be is still being worked out.

The White House is also still trying to determine if the President's action will apply only to the EPA or whether it would be a broader order affecting agencies throughout the federal government, according to the well-placed source.

Pruitt's confirmation timeline is still uncertain.

Senate Democrats have been questioning whether he can effectively lead an agency he tried to dismantle through lawsuits at least a dozen times in his current job as Oklahoma's attorney general. Despite the Democratic pushback, a vote on him nomination is now expected to occur sometime Friday.

CNN's Ashley Killough contributed to this report.

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