Senate Minority Leader Chuck Schumer (D-N.Y.) warned on Wednesday that President Donald Trump should not meet with Russian President Vladimir Putin one-on-one.

“President Trump should not meet with President Putin alone,” Schumer ominously tweeted.

President Trump should not meet with President Putin alone. — Chuck Schumer (@SenSchumer) July 11, 2018

Schumer's warning comes a day after Trump said his easiest meeting on his foreign trip to Europe over the next week could be his sit-down with Putin.

"I have NATO. I have the U.K., which is in somewhat turmoil. And I have Putin. Frankly, Putin may be the easiest of them all," Trump said Tuesday before departing for Brussels. "Who would think?"

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Schumer later tweeted that Trump's criticism of Germany before a NATO summit on Wednesday was an "embarrassment" and a signal that he is more loyal to Putin than our NATO allies.

.@realDonaldTrump’s brazen insults and denigration of one of America’s most steadfast allies, Germany, is an embarrassment. His behavior this morning is another profoundly disturbing signal that the president is more loyal to President Putin than to our NATO allies. — Chuck Schumer (@SenSchumer) July 11, 2018

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. — Chuck Schumer (@SenSchumer) July 11, 2018

On "America's Newsroom," former U.S. ambassador to the UN and former New Mexico Gov. Bill Richardson (D) said meeting with Putin is the right move for Trump.

"I think we meet with our adversaries. I just don't want us to be too friendly with them like he was with Kim Jong Un, although I supported that summit," Richardson said.

He said Trump must make it clear to Putin that Russia must cease meddling in U.S. and European elections, do something about the annexation of Crimea, work with the U.S. to remove Syrian dictator Bashar Assad from power and put the squeeze on Iran.

"I don't want the president to have a love fest with Putin. I want him to get something done to protect America's interests. That's all I want," Richardson said.

Speaking to reporters Tuesday, Trump predicted his meetings with NATO members might be more contentious than his Helsinki summit with Putin on Monday.

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