Former Vice President Joe Biden may be riding high in the current 2020 Democratic presidential polls, but that does not mean he isn't vulnerable, according to Marc Thiessen.

"I think it's really early," Thiessen, a former speechwriter for President George W. Bush, said Monday on "America's Newsroom."

"Joe Biden is the front-runner, he's pulling ahead. But that means that everybody else in the Democratic field is going to train their fire on Joe Biden, and he's is vulnerable in a lot of areas."

Thiessen pointed to recent comments Biden made about China, telling a New Hampshire crowd last week that "they're not competition for us."

BIDEN DISMISSES CHINA'S THREAT TO US AGAIN DESPITE BACKTRACKING ON HIS EARLIER COMMENTS

"No other nation can catch us, including China. I got criticized for saying that. I've spent as much time with [Chinese President] Xi Jinping as any world leader has," Biden earlier this month said.

"Joe Biden's China policies haven't worked," Thiessen said, adding that when Biden was vice president America lost hundreds of thousands of manufacturing jobs to other countries like China.

"[The Obama-Biden administration] told us those jobs are never coming back," he said. "Well, guess what. Under Donald Trump, those jobs are coming back."

Thiessen said many Obama-Biden voters who "defected" to President Trump in 2016 are doing better under the current administration than they were during the previous eight years.

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In addition, Biden is vulnerable because of his willingness to compromise on certain issues, Thiessen said.

"The left is coming after him because he wants to find a middle ground on climate change. That's not going to fly with the 'neosocialists'," he said, describing the left wing of the Democratic Party.