(CNN) The top Democrats in Congress on Friday called for President Donald Trump to cancel his upcoming summit with Russian President Vladimir Putin after the Justice Department announced indictments against 12 Russian nationals, that accused them of engaging in a "sustained effort" to hack Democrats' emails and computer networks.

"President Trump should cancel his meeting with Vladimir Putin until Russia takes demonstrable and transparent steps to prove that they won't interfere in future elections. Glad-handing with Vladimir Putin on the heels of these indictments would be an insult to our democracy," Senate Minority Leader Chuck Schumer said in a statement.

The top Democrat in the House, Rep. Nancy Pelosi of California, tweeted, "@realDonaldTrump must immediately cancel his meeting with Putin."

Pelosi had said in an earlier statement, "The stakes for the upcoming Trump-Putin meeting could not be higher. President Trump must demand and secure a real, concrete and comprehensive agreement that the Russians will cease their ongoing attacks on our democracy. Failure to stand up to Putin would constitute a profound betrayal of the Constitution and our democracy."

The call to cancel the summit came after a week in which Democrats have expressed widespread concerns about Trump's ability to sit down and challenge Putin in a one-on-one meeting, which is scheduled for Monday. White House press secretary Sarah Sanders said Friday the summit will not be canceled.

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