While the White House has condemned Donald Trump's call for a ban on Muslim immigrants as "disqualifying" and "toxic," President Barack Obama may have only himself to blame if a President Trump ever succeeds in putting his plan, or some version of it, into action.
In his efforts to work around Congress, Obama has made the aggressive use of executive power, particularly on immigration, an increasingly effective and politically accepted presidential tool. While legal scholars are divided on whether Obama has accelerated or merely continued a drift of power toward the executive branch, there's little debate that he's paved a path for his successor.
Depending on who that is, many Obama backers could rue the day they cheered his "pen-and-phone" campaign to get past Republican opposition in Congress. The unilateral steps he took to raise environmental standards, tighten gun control measures and ease the threat of deportation for millions of immigrants in the U.S. illegally, may serve as precedent for moves they won't cheer.
"Democrats have been remarkably shortsighted in embracing of this type of uber-presidency," said Jonathon Turley, a George Washington University law professor. Although Turley represents House Republicans in a challenge to Obama's health care law, he says he agrees with the policies Obama has enacted in some other actions.
"Unfortunately I think the bill will come due for many Democrats," Turley said. "In a future administration, they will hear the same arguments played back to them as they watch a different president go after a different set of priorities."
Peter Spiro, an expert on immigration and constitutional law at Temple University, doesn't believe Obama has overstepped his constitutional bounds. But he does think he's given future presidents political cover, particularly in the area of immigration.
"The next president would say, 'Well, look, President Obama was a strong defender of this and I'm just following in his footsteps,'" he said.
To be sure, the verdict is still out on how much Obama's presidency may have tipped the scales in the balance of powers between the courts, the executive and Congress. Some court challenges are undecided, most notably one contesting his second major immigration action granting temporary reprieve to millions of immigrants living in the U.S. illegally. Meanwhile, the White House has yet to decide whether to go ahead on two significant executive actions prompted by opposition in Congress — one that would expand background checks on gun sales and another that would close the prison at Guantanamo Bay and move detainees to U.S. soil.
How such actions, particularly the latter, would play out in the courts and court of public opinion would be important factors in how Obama's record is judged by history and his successor.
Experts view Obama's influence as considerable when it comes to war powers, particularly his case for killing American suspects of terrorism on foreign soil. But a paradox is evident on immigration issues — where he has very publicly seized the broad authority given to the executive and where the gap between his policies and his potential Republican successors is wide.
In 2012 and 2014, after long maintaining he did not have such authority, Obama ordered federal immigration authorities not to deport certain groups of immigrants living in the U.S. illegally. The administration asked immigrants to apply for a temporary new legal status. The White House said it was using its prosecutorial discretion — the power to determine how limited resources should be used to enforce the law.
That power has been used by all presidents on a broad range of issues, but rarely has a president called a news conference to announce it or created a formal system to use it, said Hiroshi Motomura, a University of California at Los Angeles professor and expert in immigration law.
"Every president has different priorities, but Obama has actually changed things by being more systematized and transparent and that's what led to critics and the legal challenge," Motomura said.
A future president might take the same principle into another arena, Turley argued, choosing not to enforce pollution regulation against some businesses or temporarily granting some taxpayers a reprieve.
If not a full ban on Muslim visitors, as Trump proposed, prosecutorial discretion might be used to argue for prioritizing deportation of Muslim immigrants. A president might place visitors from Muslim countries under special screening or ask them to register, moves that would have some recent precedent.
Whether such executive moves would survive a lawsuit is far from clear. In the wake of Trump's proposed ban, many legal scholars lambasted the idea but didn't label it impossible.
Congress already has granted broad authority for the president to bar "any class of aliens" entry into the United States if he determines it would be "detrimental to the interests of the United States." While some argue barring entry based on religion would be discriminatory, precisely how constitutional and legal protections against discrimination apply to a foreign national is unclear.
These murky legal questions don't always rule the day in presidential politics, noted Eric Posner, a University of Chicago law professor.
"The Supreme Court very rarely issues rulings on presidential power. It tends to try to duck cases where somebody tries to say the president doesn't have the power to do something," said Posner, who has written on the rise of executive power in "The Executive Unbound."
"When a president tries to do something, they tend to rely on a previous action from another president. It's a particularly powerful argument if the president is from another party and a particularly powerful argument if Congress did not object to what the president tried to do. Sort of like a court relies on a precedent — but not judicial precedent, political precedent."