Sen. Mark Warner Mark Robert WarnerDemocrats call for declassifying election threats after briefing by Trump officials It's time to upgrade benefits Intelligence chief says Congress will get some in-person election security briefings MORE (D-Va.) says in a new interview that President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's feud with key U.S. allies at the Group of Seven summit last week was embarrassing for the United States.

Warner said in an interview on the "Politico Money" podcast released Wednesday that Trump's defiant performance at the G-7 gathering in Canada highlighted a wedge that the president has driven between the U.S. and some of its closest allies.

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"I was embarrassed," Warner, the top Democrat on the Senate Intelligence Committee, said. "I was embarrassed that an American president acted that way, particularly when Canada and other nations were responding to the actions that Mr. Trump had taken."

In the lead-up to the G-7 summit, Trump engaged in a war of words with French President Emmanuel Macron and Canadian Prime Minister Justin Trudeau, who had both condemned Trump's decision to impose steep tariffs on imported steel and aluminum from the European Union, Canada and Mexico.

The feud escalated on Friday and Saturday as Trump called for Russia to be readmitted to the G-7, a group of leading industrialized nations, and declared after he left the summit that the U.S. would not endorse a joint communique issued by the group.

Russia was suspended from the group, then known as the Group of Eight, after it annexed Crimea from Ukraine in 2014.

Speaking at a news conference as he prepared to leave Canada on Saturday, Trump demanded that foreign leaders drastically reduce trade barriers or risk losing access to U.S. markets altogether.

"We’re the piggy bank that everybody is robbing," he said.

As the summit closed on Saturday, Trudeau issued a rebuke of Trump's proposed tariffs, declaring that Canada would not be "bullied" by the U.S. That prompted a biting response from Trump, who called the Canadian premier "very dishonest" and "weak."

Warner said that Trump's behavior undermined U.S. leadership and spited allies that Washington is deeply reliant on.

"I was frankly embarrassed — embarrassed for our country," Warner told "Politico Money." "This is not the way America leads and the way America has led the world through Democratic and Republican administrations since the Second World War."