In audio recorded by local news channel WFMZ-TV, Biden can be heard off camera telling workers at Mack Truck Lehigh Valley Operations: “I used to drive an 18-wheeler, man […] I got to.”

The clip was shared by the Republican National Committee (RNC) Research Twitter account, alongside the comment: “Joe Biden, a career politician who has been in politics for 48 years, claims he ‘used to drive an 18 wheeler.’”

Zach Parkinson, director of RNC Research, also questioned the president’s claim, sharing a 1973 opinion piece written by Biden, who was then a first-term senator.

In that article, Biden talked about how he had ridden in a “47,000-pound cargo truck” on a 500-mile-plus trip from Delaware to Ohio.

“There is zero evidence that Biden ‘used to drive an 18 wheeler,’” Parkinson tweeted.

“The extent of Biden’s trucking experience is that he rode in a truck once, for one night in 1973 (he made sure to return home by plane though).”

Parkinson also shared an Associated Press article about Biden’s 1973 journey, which was headlined “Senator observes truckers’ woes.” That article said: “Biden takes 550-mile ride.”

A Fox News report on Wednesday said the network had pressed the White House for more information on Biden’s claim and a spokesperson had pointed to a 1973 article in The Wilmington Evening Journal that discussed the trip from Delaware to Ohio.

However, the length of that journey appears to vary in different sources. In Biden’s op-ed and the Wilmington Evening Journal report, the ride was 536 miles, while the AP reported that it was 550 miles.

A White House spokesperson also reportedly pointed Fox News to Biden’s experience as a school bus driver. The president has talked about his summer job as a bus driver on several occasions.

In his 1973 op-ed, Biden wrote of the Ohio trip: “I made the trip because I wanted a firsthand account from the truckers, who say they carry 50 per cent of all the goods shipped within the United States.”

During his speech in Pennsylvania on Wednesday, Biden also joked about wanting to drive a truck.

“Well, I’m not going to say anything; I just came to drive a truck,” the president said. “And I’m not sure which one I want to drive. That one? There’s one back in the corner you can’t see. It’s the biggest damn pick-up truck you ever saw in your life.”

Newsweek has asked the White House for comment.