Former vice president Joe Biden on Wednesday dismissed the notion that the United States should be worried about China as a geopolitical competitor, prompting criticism from Sen. Bernie Sanders (I-Vt.) as well as some Republicans who argued that Biden is underestimating the world’s second-largest economy.

The argument is one Biden has frequently made in speeches throughout the years, but it is drawing increased attention due to his status as the apparent front-runner among Democrats running for president.

At a campaign stop in Iowa City, Biden pointed to his years serving as vice president and as chairman of the Senate Foreign Relations Committee, telling the crowd that there’s not a “single solitary” world leader who would trade the problems the United States faces for those confronting China.

“China is going to eat our lunch? Come on, man,” said Biden, who last week announced his bid for the 2020 Democratic presidential nomination.

He argued that Beijing has its hands full dealing with its own domestic and regional problems, such as tensions in the South China Sea — which Biden called the “China Sea” — and the “mountains ... in the west.” It was not clear to what mountains or issue Biden was referring.

“They can’t figure out how they’re going to deal with the corruption that exists within the system,” Biden said of China. “I mean, you know, they’re not bad folks, folks. But guess what? They’re not competition for us.”

Sanders, one of Biden’s competitors for the 2020 Democratic nomination, criticized Biden’s assessment of China as misguided.

“Since the China trade deal I voted against, America has lost over 3 million manufacturing jobs,” Sanders said in a tweet Wednesday night. “It’s wrong to pretend that China isn’t one of our major economic competitors. When we are in the White House we will win that competition by fixing our trade policies.”

Biden’s comments also drew a rebuke from Sen. Mitt Romney (R-Utah), the GOP’s 2012 presidential nominee.

“This will not age well,” Romney said in a tweet Wednesday night.

During the 2012 campaign, Romney had famously described Russia as America’s “number-one geopolitical foe,” but he has also argued that China is among the countries that typically “stand up with the world’s worst actors.”

Also pushing back against Biden’s remarks was Rep. Bradley Byrne (R-Ala.), who is running for Senate.

“I was just at a manufacturing plant that is being threatened by China’s corrupt trade practices,” Byrne said in a tweet. “Not to mention the national security threats they pose. Joe is plain wrong. China is absolutely a threat.”

Biden’s campaign responded on Wednesday by noting that the former vice president “underscored that, whatever challenges we face as a nation, including those posed by a rising China, they pale in comparison to the structural and social challenges that confront China itself.”

“Joe Biden believes it’s never a good bet to bet against America and the fundamental strength, resilience, and ingenuity of its people,” Biden spokesman Andrew Bates said. “If Republicans are so scared of Joe Biden that they want to take the other side of that bet to try and score political points, then they’re welcome to it.”

Trump’s campaign also seized on Biden’s comments in a tweet Thursday afternoon.

“Sleepy Joe doesn’t think China is a threat,” the tweet from the TeamTrump account reads. “Meanwhile, President Trump is working on a deal with China that puts AMERICA FIRST and protects our economy.”