President Trump arrived at the G-20 summit in Hamburg on July 7. He was greeted by Germany's chancellor Angela Merkel. (The Washington Post)

Ahead of meetings at the Group of 20 summit in Hamburg, President Trump on Friday fired off a Twitter post claiming “everyone” there was talking about the role of John Podesta, the former Hillary Clinton campaign chairman, in last year’s Russian email hacking scandal.

Trump’s tweet came amid several others in which he recounted previous meetings with world leaders there and just hours before he was scheduled to sit down with Russian President Vladimir Putin, who U.S. intelligence officials have said directed his country’s meddling in last year’s election.

Trump appeared to conflate two parts of the email scandal. Email hacked from the Democratic National Committee server surfaced first last year, while hacked email from Podesta’s personal account came out later. Podesta had no role at the DNC.

Hillary Clinton's 2016 presidential campaign chairman, John Podesta, says all Americans, regardless of party affiliation, should be concerned that a "foreign power, one that's often hostile to the United States' interest, is so actively participating in the electoral process of other nations." (Washington Post Live)

It was not immediately clear to whom Trump was referring when he said “everyone” at the G-20 summit was talking about Podesta. Several White House officials did not immediately respond to email about that subject.

Later Friday morning, Podesta responded in a string of seven Twitter posts, calling Trump "our whack job POTUS" and saying "I had nothing to do with the DNC."

Podesta relayed that he was a cross-country trip with his wife and pulled into a pit stop in West Virginia to discover Trump was tweeting about him.

"Get a grip man, the Russians committed a crime when they stole my emails to help get you elected President," Podesta wrote. "Maybe you might try to find a way to mention that to President Putin."

Podesta concluded by saying to Trump: "God only knows what you'll be raving about on twitter by the time we get to Utah."

Shortly after his Podesta post, Trump fired off another tweet, saying: “I look forward to all meetings today with world leaders, including my meeting with Vladimir Putin. Much to discuss.”

As recently as Thursday, Trump declined to say definitively that Russia had meddled in last year’s U.S. elections — a conclusion reached by multiple U.S. intelligence agencies.

“I think it could very well have been Russia, but I think it could well have been other countries,” Trump said at a joint news conference in Warsaw with Polish President Andrzej Duda. “Nobody really knows. Nobody really knows for sure.”

Trump has also accused his predecessor, Barack Obama, of not doing enough to respond to the allegations of Russian hacking.

Later Friday, Rep. Adam Schiff (D-Calif.), the top Democrat on the House Intelligence Committee, which is investigating Russia meddling, also weighed in.

"Yes, I'm sure that's the big talk at G20," Schiff wrote on Twitter. "Not climate change or trade, but why didn't John Podesta give a server that wasn't his to the CIA."