But Trump on Friday called on world leaders to allow Russian Federation back into the G7, the group of leading industrialized democracies.
"The president's support for inviting Russian Federation back into the G-7, just after they meddled in the election to support his campaign, will leave millions of Americans with serious questions and suspicions", Schumer said. Russian Federation was formerly a member of the group, then known as G-8, but was suspended after its annexation of Crimea in 2014.
Trump has repeatedly put himself at odds with practically the entire United States political and security establishment over Russian meddling in the 2016 Presidential Election.
At home, Senate Democratic leader Chuck Schumer poured scorn on the Republican president's suggestion that Russian Federation should be readmitted to the G7.
For the past week, it was an open question in official Ottawa whether Trump would actually show up, given his recent trade actions against the other G7 countries and his increasingly antagonistic comments about their approach to global relations.
Trump says he hopes to resolve what he considers unfair trade agreements with USA allies during his time at the G-7 summit in Quebec on Friday and Saturday.
A French presidential source said Trump's proposal did not seem "coherent" in view of the latest economic sanctions imposed by the United States on Moscow.
Trudeau has said the Quebec summit offers the G7 leaders an opportunity to find solutions to their many differences.
On Thursday, Macron berated Trump for imposing unilateral tariffs on imported steel and aluminium rather than go through worldwide arbitration, and for walking out of a multilateral nuclear deal with Iran.
May also lobbied for additional measures including measures to stop illicit money flows undermining democracies and more information-sharing so that Russians expelled from one country do simply enter another.
Kremlin spokesman Dmitry Peskov told reporters on Saturday the two leaders discussed the prospects for their meeting in a March phone call, and talked about locations with Vienna as a possibility.
Trump's comments on agriculture, his imposition of steel and aluminum tariffs, as well as broader disagreements on trade, climate change and the USA withdrawal from the Iran nuclear agreement, are setting the stage for some tense G7 talks.
Senate Democratic Leader Chuck Schumer said in a statement that Trump was turning US foreign policy "into an worldwide joke". Their alliance grew further as US President Donald Trump stepped up pressure specially on China both on the trade and North Korean fronts.
Despite the current G7 turmoil, Tusk said more unites the group than divides it.
"We have continued our cooperation even during hard times", Kurz said after his talks with Putin on Tuesday.
"The American president may not mind being isolated, but neither do we mind signing a six country agreement if need be", Macron said in a tweet.
"The president will travel directly to Singapore from Canada in anticipation of his upcoming meeting with North Korea's leader Kim Jong Un Tuesday", White House Press Secretary Sarah Huckabee-Sanders said in a statement.