The US president will urge the PM to resolve tensions with the EU and protect peace in Northern Ireland.
The Northern Ireland Protocol is the post-Brexit agreement which allows for special trading arrangements between the Republic of Ireland and Northern Ireland.
The government is pushing ahead with its controversial Northern Ireland Protocol Bill, which the EU and other critics claim would breach international law by suspending parts of the deal on which the UK left the bloc.has been interpreted as an attempt to neutralise suggestions from the White House that her stance on the protocol could scupper any deal, says the BBC's political editor Chris Mason.
Although apparently not intended as a criticism of Ms Truss, the comment underlines the political differences between the two leaders ahead of their meeting. The prime minister's official spokesman called it "ludicrous" to suggest Mr Biden was referring to Ms Truss in his tweet.