The Republican Tax Bill passed in the early morning hours on Saturday had something more than just tax cuts. There was a clause that will open oil drilling in the Arctic National Wildlife Refuge.

On Saturday, Republicans pushed through a massive tax overhaul bill that experts say will add up to $1.4 trillion to the budget deficit. The plan brings tax cuts to all Americans, with the largest cuts for the highest wage earners, and also slashes corporate taxes. It is the largest overhaul to the U.S. tax code since Ronald Reagan, and the first major legislative accomplishment for President Donald Trump.

Drilling provision brings controversy

The tax bill generated some immediate criticism for its massive addition to the deficit, something Republicans had railed against during Obama's two terms in office, and also for some smaller provisions added in to entice on-the-fence Republicans to support the measure. One of those was a proposal to open oil drilling in the Wildlife Refuge in Alaska, which had been long sought by Senator Lisa Murkowski.

Some Democrats tried to bring attention to the oil drilling provision in the hours leading up to the tax bill vote. Kamala Harris, a Democrat from California, tweeted about the Arctic National Wildlife Refuge provision in an effort to drum up opposition, but it was to no avail as the bill eventually passed along party lines.

Some other longtime drilling opponents, including Democrat Maria Cantwell from Washington, also tried to bring attention to the drilling provision.

"It's critically important, and I don't think anybody knows it is stuck in a tax bill," she told the New York Times in the days leading up to the vote. "It's been around for thousands of years, and for no good reason, we're going to change it? Is there no such thing as a special place?"

A 'critically important landscape'

Even some Republicans tried to oppose plans to open up drilling in the Arctic National Wildlife Refuge.

A group of 12 House Republicans sent a letter to Speaker Paul Ryan asking to preserve what they said is a "critically important landscape." The Arctic National Wildlife Refuge encompasses 1.2 million acres that are home to a number of animals including caribou and polar bears as well as deep deposits of natural resources. There have been proposals for decades to open the land for drilling, which has been opposed by Democrats and conservations groups alike.