President Trump speaks during his announcement of federal appeals court Judge Neil Gorsuch as his nominee for the Supreme Court. (Jabin Botsford/The Washington Post)

President Trump’s Twitter assault on the “so-called judge” who put a nationwide hold on the president’s executive order on immigration has motivated Democrats to challenge Trump’s choice for the Supreme Court, Judge Neil Gorsuch, on an important but elusive issue.

Is Gorsuch independent enough, they ask, to stand up to the president who picked him?

As the legal battle over Trump’s immigration directive shows, Gorsuch’s nomination lands at a time when the Supreme Court is likely to be called upon to review what Trump already has shown to be a broad reliance on executive power.

It is difficult for appeals court judges such as Gorsuch to point to past decisions to demonstrate independence, and few are called upon to make definitive rulings on a president’s powers.

(Bastien Inzaurralde/The Washington Post)

Those who have studied Gorsuch’s record say he has shown a skepticism about government power but warn against weaving a philosophy from a series of unrelated votes.

It is already clear that Trump’s broadsides against U.S. District Judge James L. Robart, who put the president’s immigration order on hold, have placed Gorsuch in a difficult position. Democrats have been quick to exploit it.

“When [Trump] attacks the independence of the judiciary, I think it does focus on the fight before us now,” Sen. Amy Klobuchar (D-Minn.) said Sunday on ABC’s “This Week,” adding, “We want to see a nominee that is independent.”

Sen. Patrick J. Leahy (D-Vt.) has picked up the theme. “We need a nominee for the Supreme Court willing to demonstrate he or she will not cower to an overreaching executive,” he said.

Senate Minority Leader Charles E. Schumer (D-N.Y.) weighed in as well. “With each action testing the Constitution, and each personal attack on a judge, President Trump raises the bar even higher for Judge Gorsuch’s nomination to serve on the Supreme Court,” Schumer said in a statement. “His ability to be an independent check will be front and center throughout the confirmation process.”

It’s a difficult situation for Gorsuch and those shepherding his nomination. On the one hand, they want to energize the base by portraying Gorsuch as a solid conservative worthy of the late justice Antonin Scalia’s place on the court.

But at the same time, they must combat the view that he would be a rubber stamp for a president whose hard-charging style shows little patience for the separation of powers.

The first part seems easy.

Gorsuch, 49, who has served for 10 years as a judge on the U.S. Court of Appeals for the 10th Circuit in Denver, is a well-credentialed Republican and an outspoken conservative all the way back to his high school days. His writings on and off the bench show more of an ideological kinship with Scalia than the more-moderate justice for whom Gorsuch once worked, Anthony M. Kennedy.

Gorsuch would not have made Trump’s list of 21 candidates without a thorough vetting from the conservative activists who advised the president and who are delighted by his selection.

But it is not easy to look at a judge’s past rulings and make ironclad predictions about his future on the Supreme Court. Some opinions are open to interpretation, some reflect a required conformance to precedent and some major issues simply never land on his docket.

On the question of executive power, there are no more than “hints,” according to Jonathan H. Adler, a law professor at Case Western Reserve University who has written about Gorsuch’s views questioning judicial deference to executive agencies.

“Chevron deference” is based on a long-standing Supreme Court decision that is little known to the public but vitally important to the functioning of the federal government. It directs courts to grant wide leeway to executive branch agencies when they reasonably interpret acts of Congress that are ambiguous. This approach obviously works to the benefit of the president and those put in charge of federal agencies.

But Gorsuch has written that it allows “executive bureaucracies to swallow huge amounts of core judicial and legislative power and concentrate federal power in a way that seems more than a little difficult to square with the Constitution of the framers’ design.”

That indicates a skepticism of government, Adler said, but does not reflect detailed views on deference owed the president.

Few federal judges have definitive rulings on such a question or opportunities to prove the kind of independence Democrats are demanding. Adler said his review of the Gorsuch record did not uncover any reason to believe that he would be overly deferential to the president.

“If Donald Trump were looking for someone who would be a green light to broad assertions of executive power, Neil Gorsuch is not that,” Adler said.

Such questions of independence are not new, of course; President Obama’s nominees faced them as well.

Republicans point out that Obama, too, was combative in approaching the courts. He took the highly unusual step of scolding the Supreme Court for campaign finance decisions as the justices sat at his 2010 State of the Union address.

And while the court was considering but had not ruled on the constitutionality of the Affordable Care Act, many thought Obama was applying pressure by publicly opining that it would be “unprecedented” for the court to overturn the law.

But Trump’s tweets about Robart, who has been on the bench since 2004, were personal, and exaggerated the effects of the judge’s temporary restraining order imposing a nationwide stop to Trump’s order.

“Just cannot believe a judge would put our country in such peril. If something happens blame him and court system. People pouring in. Bad!” Trump tweeted Sunday afternoon.

Sen. Ben Sasse (R-Neb.) is a strong Gorsuch supporter who calls the judge “a rock star.” But Sasse is also a longtime critic of Trump, and said Sunday on ABC’s “This Week” that the president’s actions weren’t helpful.

“We don’t have so-called judges, we don’t have so-called senators, we don’t have so-called presidents. We have people from three different branches of government who take an oath to uphold and defend the Constitution,” Sasse said. “And it’s important that we do better civics education for our kids.”

Curt Levey, a conservative legal activist, said Trump’s controversial comments and his intended disruptive role will transform the Senate hearing and debate on Gorsuch.

“This confirmation process may well be different, with President Trump’s tweets and other remarks driving the flow,” Levey wrote in an op-ed in the Hill newspaper, adding, “Don’t be surprised if Democrats question Trump’s legitimacy to make Supreme Court nominations and hold Gorsuch’s nomination hostage to extraneous demands on the president.”

Mike DeBonis contributed to this report.