MAD DUCK: Obama actions on public lands may be difficult for Trump to undo.

President Barack Obama could cement his environmental legacy by taking executive action to designate nearly 4 million acres of Western land as national monuments before leaving office next month.

And it may be one legacy of the Obama administration that incoming President Donald Trump will have a hard time unraveling after he takes office.

But whether Obama goes that route is still up in the air. Arizona Sens. John McCain and Jeff Flake said Monday that “credible sources” within the agencies considering the designation found “significant unresolved issues that prevent their recommending the designation of a new national monument” around the Grand Canyon.

At issue is a call by environmentalists for Obama to use the authority granted by the Antiquities Act to protect areas around the Grand Canyon in Arizona, the Bears Ears site in Utah and Gold Butte in Nevada.

If we want to get serious about reducing debt and funding our trillions in unfunded entitlements, selling off western lands (Washington owns nearly 60% of the U.S. from the Front Range to Alaska) would be a good place for a gutsy administration to start.