(Bloomberg) -- Top congressional Democrats urged President Donald Trump to call off his meeting with Russian President Vladimir Putin after a grand jury in the U.S. indicted 12 Russian intelligence officers for hacking a Democratic Party computer network during the 2016 U.S. presidential campaign.

“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,” Senate Minority Leader Chuck Schumer of New York said in a statement Friday. “Glad-handing with Vladimir Putin on the heels of these indictments would be an insult to our democracy.”

Senator Jack Reed of Rhode Island, the top Democrat on the Senate Armed Services Committee, was among others who weighed in.

“In light of this stunning indictment by the Justice Department that these Russian conspirators attacked our democracy and were communicating with Americans to interfere in our election, President Trump should immediately cancel his meeting with Vladimir Putin,” Reed said.

Trump has repeatedly called the investigation by Special Counsel Robert Mueller a “witch hunt,” and some of his allies have said the probe should be brought to a quick conclusion.

Most Republican leaders, including Senate Majority Leader Mitch McConnell, made no statements immediately after the indictments were announced at the Justice Department. But House Foreign Affairs Chairman Ed Royce, a California Republican, said in a statement that Trump should “should use today’s indictments to challenge Vladimir Putin" at the summit meeting.

“For years, we’ve known about the Kremlin’s campaign to weaponize information and chip away at our institutions,” Royce said. “And yet for years, we have not done enough to counter it.”

Eighteen Democratic members of the House Foreign Affairs panel urged Trump in a letter to cancel the meeting, saying that "due to your constant expressions of sympathy for Vladimir Putin" the lawmakers "do not have confidence that you can faithfully negotiate with the Russian leader."

No ‘Knowing Involvement’

The White House didn’t immediately respond to a request for comment. Earlier, White House spokeswoman Lindsay Walters responded to the indictments, saying in a statement that “today’s charges include no allegations of knowing involvement by anyone on the campaign and no allegations that the alleged hacking affected the election result.”

The announcement Mueller obtained indictments of the 12, all members of Russia’s military intelligence agency, comes just three days before Trump and Putin are to meet in Helsinki. The Russians are charged with stealing usernames and passwords of volunteers in Democrat Hillary Clinton’s campaign, including its chairman John Podesta. They also allegedly hacked into the computer network of the Democratic National Committee and the Democratic Congressional Campaign Committee in an operation starting around March 2016.

Podesta said in an interview that he wouldn’t call on Trump to cancel the meeting with Putin. Instead “maybe he should ask Putin to turn over the 12 people indicted to the UnitedStates for trial,” Podesta said.

U.S. and Russian officials say next week’s talks will touch on every major point of tension between the two countries -- the Kremlin’s meddling in the 2016 election, its military incursions into Ukraine and Syria, Moscow’s saber-rattling toward NATO allies and the American economic sanctions intended to punish Russia for its actions.

Trump said Friday not to expect a “Perry Mason” moment when he again speaks with Putin on Monday over Russia’s meddling in the 2016 election, but promised to bring up the matter.

“I will absolutely, firmly ask the question” about interference in the U.S. election, Trump said at a news conference with U.K. Prime Minister Theresa May at Chequers, her country estate. But he predicted Putin wouldn’t confess.

No ‘Perry Mason’ Moment

“I don’t think you’ll have any ‘Gee, I did it, I did it, you got me,”’ Trump said. Referring to a TV courtroom drama aired in the 1950s and 1960s that often featured a dramatic, last-minute confession, he added, “There won’t be a Perry Mason here, I don’t think, but you never know what happens, right?"

Other Democrats joining the call to jettison the meeting included Senator Richard Blumenthal of Connecticut and Representative Adam Schiff of California, the top Democrat on the House Intelligence Committee. Schiff said on CNN that Trump should “cut his losses on this disastrous trip to Europe” and come back without engaging with the Russian leader.

Others were more nuanced. Senator Mark Warner of Virginia, the top Democrat on the Senate Intelligence Committee, told reporters that Trump shouldn’t meet alone with Putin, added that he is “afraid the president could be take advantage of” due to his lack of preparation. He also called on the president and his allies to “immediately cease and desist from calling the Mueller investigation a witch hunt.”

House Minority Leader Nancy Pelosi stopped short of calling for a cancellation. Instead, she said Trump should use the meeting to secure a comprehensive pact that the Russians will stop their “ongoing attacks on our democracy.”

“Failure to stand up to Putin would constitute a profound betrayal of the Constitution and our democracy,” Pelosi said in a statement.

--With assistance from Justin Sink, Margaret Talev, Erik Wasson and Jennifer Epstein.

To contact the reporters on this story: Laura Litvan in Washington at llitvan@bloomberg.net;Tom Schoenberg in Washington at tschoenberg@bloomberg.net

To contact the editors responsible for this story: Joe Sobczyk at jsobczyk@bloomberg.net, Laurie Asséo

©2018 Bloomberg L.P.