Hillary Clinton predicted in an interview Friday that President Donald Trump will receive primary challenges from Republicans when he seeks re-election in 2020.

British reporter Matt Frei on Channel 4 News noted to Clinton that Trump has already said he will seek a second term and he could very well win again. The last three U.S. presidents have been re-elected, two of them with greater margins of victory than the first time.

“Well, we don’t know,” Clinton said. “We have no way of knowing that … Right now, his approval is very, very low.”

Clinton said some of Trump’s voters in 2016 only went for him because they wanted a Supreme Court seat or desired a “big tax cut.”