Congressional Democrats and at least one Republican have called on Trump to pull out of Monday's meeting unless he is willing to make Russian election-meddling the top issue.
Before and during the North Atlantic Treaty Organisation summit, the US President again berated European nations for falling short of the alliance's goal to have all member-states devote 2 per cent of GDP to the military.
His comments follow months of Trump jabs aimed at longtime U.S. allies over trade policies.
"I don't think you'll have any 'Gee, I did it, I did it".
"America and the European Union are best friends", Tusk wrote.
When Face the Nation's Jeff Glor told Trump that "a lot of people might be surprised to hear you list the European Union as a foe before China and Russia", Trump made it sound as though it upset him to have to challenge Europe, his ancestral homeland.
Trump and his aides have been working through the weekend to soften expectations for tangible results from the Russian Federation meeting.
Trump has suggested there likely will be few quantifiable results from the summit, telling CBS in an interview this weekend he is going into the meeting with "low expectations". Another frame for Trump's criticism of Europe was white nationalism, as he also said last week that it was a shame that European countries were allowing their cultures to be erased by allowing in immigrants.More news: Chelsea's incredibly short send off to Antonio Conte
More news: Serena Williams: Wimbledon final is 'awesome' after having baby
More news: US hits China with $34B round of tariffs; Beijing strikes back
Trump and Putin have met twice before, during worldwide summits past year in Germany and Vietnam. Last November, in Vietnam, they agreed to maintain open military channels of communications between their forces in Syria. Most US officials see Putin as an unsavoury character on the world stage. He said his problems with the European Union centered on "what they do to us in trade".
Near Trump's hotel, police roped off a group of about 60 mostly male pro-Trump demonstrators waving American flags.
Bolton was skeptical as to whether Trump would press Putin to extradite the 12 Russian agents to the United States, noting that the two countries do not have an extradition agreement.
Donald Trump says he may ask Vladimir Putin during their Monday summit meeting to extradite to the United States 12 Russian intelligence officers accused of attempting to interfere with the 2016 presidential election.
Putin is regarded as creating a culture of violence and impunity that has resulted in the killing of some Russian journalists.
Russia's Constitution forbids the extradition of its citizens.
"I hadn't thought of that", Trump said. "But I will absolutely, firmly ask the question", he added. "Whoever says we are foes is spreading fake news", Mr Tusk said on Twitter. I believe it's really good.