Former Vice President Joe Biden used conservative British Prime Minister Boris Johnson‘s victory as proof that Democrats should not lean too far left in their 2020 fight against President Donald Trump.

Johnson’s Conservative Party won an overwhelming majority in Thursday’s election, and took several parliamentary seats from the opposing Labour Party.

“Look what happens when the Labour Party moves so, so far to the left. It comes up with ideas that are not able to be contained within a rational basis quickly,” Biden said.

Biden also claimed that Johnson’s victory will make the public believe Trump has greater odds of re-election.

“You’re also going to see people saying, ‘My God, Boris Johnson, who is kind of a physical and emotional clone of the president, is able to win,’” he said.

Biden has presented himself as a moderate alternative to Trump, criticizing the most progressive proposals by fellow candidates Elizabeth Warren and Bernie Sanders.

He has attracted a solid base of supporters, although mainly amongst older voters and African-Americans.

A national average of polling data on RealClearPolitics shows Biden polling the best with 28.4 points, ahead of Sanders by a 10 point lead. However, he trails South Bend mayor Pete Buttigieg in Iowa.

Some have criticized Biden for being too bipartisan, but he has defended his ability to work with both parties.

“Presidents are supposed to be able to persuade and work something out,” he said, adding that he thinks he has “been relatively good at doing that.”