Senate Minority Leader Charles E. Schumer (D-N.Y.) and House Minority Leader Nancy Pelosi (D-Calif.) speak to young undocumented immigrants in Washington last year. (Jose Luis Magana/AP)

The top two Democrats in Congress on Wednesday issued a sharp rebuke of President Trump as he began a week of high-stakes diplomacy in Europe, calling his behavior at the outset of a NATO gathering “an embarrassment.”

Senate Minority Leader Charles E. Schumer (D-N.Y.) and House Minority Leader Nancy Pelosi (D-Calif.) issued a joint statement in response to comments Trump made at a breakfast meeting in Brussels in which he said he considered Germany to be “captive to Russia” because it is getting much of its energy from the nation.

“President Trump’s brazen insults and denigration of one of America’s most steadfast allies, Germany, is an embarrassment,” Schumer and Pelosi said in the statement. “His behavior this morning is another profoundly disturbing signal that the President is more loyal to President Putin than to our NATO allies.”

Trump’s itinerary in coming days also includes a summit in Helsinki with Russian President Vladi­mir Putin that has already riled some NATO leaders, who fear that Trump is seeking to forge a stronger relationship with Putin than with traditional U.S. allies.

Democrats in Congress are pressing Trump to confront Putin on Russia’s interference in the 2016 election. Trump has continued to highlight Putin’s denials of such activity.

“If the President leaves the Putin meeting without ironclad assurances and concrete steps toward a full cessation of Russian attacks on our democracy, this meeting will not only be a failure — it will be a grave step backward for the future of the international order and global security,” Schumer and Pelosi said in their statement. “A successful meeting means real action, now.”

“The President needs to remember that, as Commander-in-Chief, his duty is to protect the American people from foreign threats, not to sell out our democracy to Putin,” the two Democratic leaders said.

Trump’s comments about Germany came during a meeting with NATO Secretary General Jens Stoltenberg. In front of television cameras, Trump continued to complain about Europe’s lagging defense spending and castigated Germany for beginning construction on a second natural gas pipeline to Russia.

“We have to talk about the billions and billions of dollars that’s being paid to the country we’re supposed to be protecting you against,” Trump said, referring to European purchases of Russian natural gas.

Under its rules, the 29 member states of the North Atlantic Treaty Organization are required to come to the aid of any member state subject to an armed attack.