Trump is to arrive in Britain Monday for the two-day summit, during which he is to hold several bilateral meetings with North Atlantic Treaty Organisation heads of state, including French President Emmanuel Macron and German Chancellor Angela Merkel.
Mr Trump later said he was "absolutely cognisant" of the importance of not interfering in other countries' elections. Trump has never made any secret of his affinity for the British prime minister.
British Prime Minister Boris Johnson said on Friday it would be "best" if U.S. President Donald Trump does not get involved in Britain's election when he visits London for a North Atlantic Treaty Organisation summit next week.
"We are on the right track, but we can not be complacent", Stoltenberg said.
The Conservatives will be wary of any endorsements or comments from Mr Trump during the visit, a week before the public goes to the polls on December 12.
Trump has also criticised opposition Labour leader Jeremy Corbyn, but this risks backfiring in a country where Trump himself is deeply unpopular.
Speaking about the prime minister at a rally in Buckley, Wales, Mr Farage - who had entered the room to Kanye West's 2010 song Power - told party supporters on Monday "you may well be related to one of his many children".
Labour's Corbyn has mentioned Johnson will dump elements of Britain's broadly cherished well being service to US companies after Brexit, which Johnson has denied.
Flanked by senior Cabinet minister Michael Gove and former Labour MP Gisela Stuart, Mr Johnson warned voters that Brexit would be further "delayed, denied" if they do not deliver a Tory majority.
Nigel Farage says a second referendum would cause even more division and ignoring the vote for Leave would be the death of democracy.
Sooner or later of a cellular telephone-in on Farage's radio gift final month, Trump instant he and Johnson win an electoral pact - something the Tories fill strongly rejected.
The US president is also set to meet Prime Minister Boris Johnson during the trip, with White House deputy press secretary Judd Deere saying the pair were looking forward to it.
Anne Sacoolas claimed diplomatic immunity and subsequently returned home, but Dunn's family want her to come back to Britain to face justice.
Plaid Cymru leader Adam Price said Mr Farage was wrong to defend the U.S. president.
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