Trump's ban keeps roiling, Pence comments

US President Donald Trump on Sunday ramped up his criticism of a federal judge who blocked a travel ban on seven mainly Muslim nations and said courts were making US border security harder, intensifying the first major legal battle of his presidency.

In a series of tweets that broadened his attack on the country's judiciary, Trump said Americans should blame US District Judge James Robart and the court system if anything happened.

The Republican president labeled Robart a "so-called judge" on Saturday, a day after the Seattle jurist issued a temporary restraining order that prevented enforcement of a 90-day ban on citizens from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen and a 120-day bar on all refugees.

A US appeals court later on Saturday denied the government's request for an immediate stay of the ruling.

Vice-President Mike Pence defended Trump earlier on Sunday, even as some Republicans encouraged the businessman-turned-politician to tone down his broadsides against the judicial branch of government.

"The president of the United States has every right to criticize the other two branches of government," Pence said on NBC's Meet the Press program.

US Senator Patrick Leahy, the ranking Democrat on the Senate Judiciary Committee, said Trump seems intent on precipitating a constitutional crisis.

Some Republicans also expressed discomfort with the situation.

"I think it is best not to single out judges for criticism," Senate Majority Leader Mitch McConnell said on CNN. "We all get disappointed from time to time at the outcome in courts on things that we care about."

Republican Senator Ben Sasse, a vocal critic of Trump, was less restrained.

"We don't have so-called judges ... 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," he said on ABC News.

The ruling by Robart, appointed by former Republican President George W. Bush, coupled with the decision by the 9th US Circuit Court of Appeals in San Francisco to deny the government's request for an immediate stay of the ruling dealt a blow to Trump barely two weeks into his presidency.

Trump told reporters at his private Mar-a-Lago resort in Florida late on Saturday: "We'll win. For the safety of the country we'll win."