Joe Biden did not support Brexit and says it is “not how we would have preferred it to be”.
He was vice president when Barack Obama appealed for the UK to stay in the European Union. Mr Obama said the UK would end up at the “back of the queue” for a trade deal.
In September Mr Biden wrote on Twitter: “Any trade deal between the US and UK must be contingent upon respect for the [Good Friday] Agreement and preventing the return of a hard border. Period”
It was the first in a series of discouraging comments linking potential effects of Brexit to a future trade deal.
The following month he wrote: “We can’t allow the Good Friday Agreement that brought peace to Northern Ireland to become a casualty of Brexit.”
In late November Mr Biden reiterated that he did not want to see a guarded border in Ireland.
Asked what his message to Brexit negotiators was, Mr Biden said: “We do not want a guarded border. We want to make sure. We’ve worked too long to get Ireland worked out.
“And I talked with the British prime minister, I talked with the Taoiseach, I talked with others, I talked to the French.
“The idea of having a border north and south once again being closed is just not right, we’ve just got to keep the border open.”
Last month Mr Biden delivered a further blow, suggesting he would concentrate on building up industries at home before a trade deal.
He said: “I want to make sure we’re going to fight like hell by investing in America first.
“I’m not going to enter any new trade agreement with anybody until we have made major investments here at home and in our workers.”
An advising figure to the president-elect has also suggested that Mr Biden will ‘will not prioritise UK-US trade deal in first 100 days’ in the White House.
Instead, he will focus on domestic issues, such as coronavirus relief and climate change.
In Mr Biden’s election campaign events he is not known to have ever mentioned a trade deal with the UK.