Members of Congress said on Wednesday that they “have not come to any final conclusions” in their investigation into whether any presidential candidates colluded with Russian intelligence operatives during last November’s election.

“The issue of collusion is still open,” Sen. Richard Burr, the North Carolina Republican who chairs the Senate Intelligence Committee, said at a widely attended hearing in the Capitol Building. He added that the committee “continues to investigate both intelligence and witnesses,” and that he hopes the investigation will conclude by the end of the year.

Burr and Sen. Mark Warner of Virginia, the ranking Democrat on the Senate Intelligence Committee, stressed that while they have not obtained any proof of a campaign colluding with Russia, and that last November’s vote tallies were not altered by Moscow’s efforts, there is little question that Russia tried to interfere in the process. Warner said there was a “large consensus that [Russian operatives] hacked into political files and released those files in an effort to influence the election.”

“Russian intelligence is determined, clever, and I reckon that every campaign official should take this seriously as we approach the coming elections,” Burr said.

The lawmakers emphasized the breadth of their investigation, which began in January. A graphic poster onstage at the press conference indicated their inquiry had so far involved more than a hundred interviews and yielded more than 4,000 pages of transcripts.

The press conference came two days after Facebook gave congressional investigators more than 3,000 political ads displayed on the social media site that had been traced to Russia. Burr and Warner said they would not be releasing these ads, but Burr said the ads targeted “every group in America.”

“They were indiscriminate,” Burr said. “[The] overall theme of Russia’s involvement in the U.S. election was to create chaos at every level. They have been pretty darn successful.”

According to the lawmakers, Russia’s interference campaign continues to this day.

“The Russian active measure efforts did not end on Election Day 2016,” Warner said. “They did not just take place in the United States. We’ve seen concerns raised in France, the Netherlands, Germany.”

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