His lawyer Rudy Giuliani told Fox News that it would be wrong for Mr Trump to concede.
• If the election result is challenged, it would first require legal teams to challenge it in the state courts.
Corey Lewandowski on what the Trump campaign believes is a concrete example of voter fraud in Pennsylvania
Democrat Joe Biden has been declared president-elect, but President Donald Trump is still planning legal challenges to the results in some key states.
His lawyer Rudy Giuliani told Fox News that it would be wrong for Mr Trump to concede because: “There is strong evidence that this was an election that in at least three or four states, and possibly 10, it was stolen.”
The Trump campaign is yet to provide this “strong evidence” but says it plans to lodge lawsuits in several key states on Monday.
Here’s what we know so far.
Mr Giuliani says further lawsuits will be filed over a lack of access for poll watchers in the state.
Poll watchers are people who observe the counting of votes, with the aim of ensuring transparency. They are allowed in most states as long as they are registered before election day.
In some areas this year, there were restrictions put in place before election day, in part due to coronavirus. There are also capacity limits set to avoid intimidation.
A 20-foot (six-metre) perimeter was set in the Philadelphia counting facility but this was challenged and a court ruling on Thursday said it should be reduced to six feet – as long as poll watchers adhered to Covid-19 protocols.
The Trump campaign has filed a federal lawsuit accusing election officials of violating the judge’s order.
Mr Giuliani said: “Even when a court order was obtained to allow the Republican inspectors to get six feet closer, they moved the people counting the ballots six further feet away.”