Donald Trump's Supreme Court nominee, Neil Gorsuch, on Wednesday described as "demoralizing" and "disheartening" the U.S. president's Twitter attacks on a judge who suspended Trump's travel ban on seven Muslim-majority countries, a spokesman for Gorsuch said.

Gorsuch's comments came as a federal appeals court in San Francisco was expected to decide in coming days on the narrow question of whether U.S. District Judge James Robart acted properly in temporarily halting enforcement of Trump's ban.

A Republican strategist hired by the White House to help guide Gorsuch's nomination through the U.S. Senate said that Gorsuch, himself an appeals court judge, used those words when he met with Democratic Senator Richard Blumenthal.

Trump, who took office on Jan. 20, took to Twitter over the weekend to condemn the Friday night order by Robart that placed on hold the president's Jan. 27 temporary travel ban on people from the seven countries and all refugees.

Trump called Robart a "so-called judge" whose "ridiculous" opinion "essentially takes law-enforcement away from our country." Trump's administration appealed Robart's ruling to a three-judge federal appeals panel, which heard oral arguments on Tuesday.

Presidents are usually hesitant to weigh in on judicial matters out of respect for the U.S. Constitution, which ensures a separation of powers among the president's executive branch, Congress and the judiciary.

The Republican-led Senate on Wednesday confirmed immigration hardliner Republican Senator Jeff Sessions to be the next attorney general despite strong Democratic opposition.

Trump says his executive order aims to head off attacks by Islamist militants. The order, the most divisive act of Trump's young presidency, sparked protests and chaos at U.S. and overseas airports. Critics said the ban unfairly targeted people for their religion.

"I don't ever want to call a court biased," Trump told hundreds of police chiefs and sheriffs from major cities at a meeting in a Washington hotel on Wednesday. "So I won't call it biased. And we haven't had a decision yet. But courts seem to be so political." 

Trump nominated Gorsuch on Jan. 31 to succeed conservative Justice Antonin Scalia on the nine-member Supreme Court. Scalia died a year ago this month.

Blumenthal, a member of the Judiciary Committee that will hold a confirmation hearing on Gorsuch, said the nominee had a responsibility to reassure Americans that he would be an open-minded and independent jurist by going public with his concerns about Trump.

PRESIDENTIAL POWERS

The appeals court decision on whether to reinstate the ban, will be just a first step in a fast-moving case.

The courts will ultimately have to address questions about the extent of the president's power on matters of immigration and national security. Traditionally, judges have been extremely cautious about stepping on the executive branch’s authority in such matters, legal experts say, although some note that the implementation of Trump's order presents unique issues.

Trump's order barred travelers from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen from entering for 90 days and all refugees for 120 days, except those from civil war-torn Syria, who are subject to an indefinite ban.

Also at issue is whether the order violates a provision of the U.S. Constitution that prohibits laws favoring one religion over another, along with relevant discrimination laws.

PRESIDENTIAL DIRECTIVES

Trump, a Republican, has made extensive use of presidential directives that bypass Congress and has appeared to be taken aback by legal challenges to his travel order.

He praised a federal judge in Boston who earlier ruled in his favor on the travel ban as a "highly respected" jurist whose findings were "perfect."

Last year, Trump accused Indiana-born U.S. District Judge Gonzalo Curiel of bias in overseeing a lawsuit against one of Trump's businesses, Trump University, because of his Mexican heritage.

Democrats and other critics have called Trump's comments toward the judiciary an attack on a core principle of American democracy: that the courts are independent and uphold the rule of law.

At the meeting with law enforcement officials, Trump read from the law he cited to justify the travel ban, quoting it in fragments and sprinkling in bits of interpretation. He said the law clearly allowed a president to suspend entry of any class of people if he determined them to be a detriment to national security.

The matter is likely to go to the U.S. Supreme Court, which is ideologically split with four liberal justices and four conservatives pending Senate action on Trump's nomination of Gorsuch, a conservative jurist.

U.S. State Department figures showed that 480 refugees had been admitted to the United States since Robart's order went into effect, including 168 on Wednesday. Of those admitted, 198 were from war-torn Syria.