London (CNN) As one of the world's most renowned scientists, Stephen Hawking is regularly called on to help explain the universe's more mysterious phenomena.

But asked to account for Donald Trump's political rise Tuesday, the British theoretical physicist was stumped.

"I can't," Hawking told CNN affiliate ITV's "Good Morning Britain" program.

"He is a demagogue, who seems to appeal to the lowest common denominator."

The Trump campaign did not immediately reply to a message requesting comment.

Frosty response to Trump in UK

Hawking is not the first British public figure to make comments critical of the presumptive Republican nominee.

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Trump's comments on Islam on the campaign trail -- including a claim that Britain has a "massive Muslim problem" -- have provoked a backlash in the UK, with British Prime Minister David Cameron and London Mayor Sadiq Khan among the many politicians weighing in against the businessman-turned-politician.

Hawking: Stay in the EU

Hawking, who has previously joked about his dismay at the U.S. presidential race, also weighed in on the Brexit issue , saying he hoped Britons voted to remain in the European Union when a referendum is held on the issue next month.

"Gone are the days we could stand on our own, against the world. We need to be part of a larger group of nations, both for our security, and our trade," the 74-year-old said.

"There are two obvious reasons why we should stay in. The first is that it promotes the mobility of people. Students can come here from EU countries to study, and our students can go to other EU universities," he said.

"More importantly, at the level of research, the exchange of people enables skills to transfer more quickly, and brings new people with different ideas. Without this exchange we would become more culturally isolated and insular, and ultimately more remote from where progress is being made."

Hawking also brushed off a suggestion he had benefited from a surge of interest following actor Eddie Redmayne's Oscar-winning portrayal of him in the 2014 movie "The Theory of Everything."

"I had many fans before Eddie Redmayne played me," he said.