President Trump stood before a World War II-era battleship to declare the port city of Wilmington a World War II “Heritage City”.
As storm clouds gathered, he pointed to a bolt of lightning and said it was God saluting the event.
He honoured war veterans, including 97-year-old Hershel “Woody” Williams, the sole surviving Marine from the war to receive the Medal of Honour.
The West Virginia native fought in the Battle of Iwo Jima in the Pacific.
“He’s 100% sharp,” President Trump said of Mr Williams, who travelled to the key battleground state with the president aboard Air Force One.
“I know a 78-year-old who’s not so sharp,” President Trump added, a clear allusion to Mr Biden.
White House press secretary Kayleigh McEnany had insisted earlier this week that there was no “political purpose” to President Trump’s visit to North Carolina.
But when the president landed in Wilmington, he lost no time in criticising Mr Biden.
“This is the most important election in the history of our country. I really believe that, because we’re running against people that have got some big issues,” he told supporters on the airport tarmac.
“They have got some big, big problems. They’re stone cold crazy.”
President Trump won North Carolina by 3.6 percentage points in 2016, but polls are showing an extremely close race taking shape in a state that generates 15 electoral votes for its winner.
The president’s visit to North Carolina comes as county boards start sending absentee ballots to voters on Friday. Vice President Mike Pence will follow the president by visiting Raleigh on Thursday.
Through September 1, more than 591,000 ballot requests had been received, compared with approximately 36,500 through the same period in 2016, the state elections board said on Wednesday.
More than half of the absentee ballots, or approximately 313,000, have been requested by Democrats. Republicans have requested more than 93,000 and registered unaffiliated voters account for approximately 183,000 ballot requests.
Mr Biden released a statement in advance of the trip saying that President Trump has not provided North Carolina with the road-map and resources needed to protect businesses, schools and families from coronavirus.
“Instead of honouring the sacrifice of our front-line heroes, President Trump has repeatedly ignored public health guidance for political purposes,” Mr Biden said.
Wilmington has been home to the Battleship North Carolina since 1962. The ship is now a floating museum. On September 2, 1945, Japan’s formal surrender took place aboard the USS Missouri, anchored in Tokyo Bay.
