"I think it's just another excuse. I don't believe it," Trump said in an interview recorded on Saturday but broadcast Sunday on Fox News.
"I think it's ridiculous," Trump said.
In the interview Trump touched on other issues -- questioning US commitment to the "one China policy" without concessions from Beijing, criticizing "out of control" Pentagon arms contracts, and hailing Exxon CEO Rex Tillerson, who is under consideration for secretary of state, as "a world class player."
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But the controversy over the latest US intelligence consensus on Russia and Trump's skepticism of the findings dominated the conversation at a time of deepening political divisions over how to respond to the hacking attacks.
Two top Republican senators -- John McCain and Lindsey Graham -- joined leading Democrats Sunday in calling for greater public disclosure about "recent cyber attacks that have cut to the heart of our free society."
"This cannot become a partisan issue. The stakes are too high for our country," they said in a joint statement with Chuck Schumer, the incoming Democratic leader in the Senate, and Jack Reed, the ranking Democrat on the Senate Armed Services Committee.
"These are the same people that said Saddam Hussein had weapons of mass destruction."
They pledged to work across party lines to have the incidents investigated, but other Republicans said the evidence does not support the conclusions that the Russian meddling was aimed at helping Trump.
"These are the same people that said Saddam Hussein had weapons of mass destruction," Trump's transition team said on Saturday, in an extraordinary rebuke of the spy agency.
Adam Schiff, the ranking Democrat on the House Intelligence Committee, said the hacking was definitely the work of the Russians.
"This was not China. This wasn't a 400 pound guy in New Jersey or anyone else," Schiff said, mocking similar comments Trump has made. "This was the Russians."
He added: "The fact that we have a President-elect who is willing to disregard the overwhelming evidence of the intelligence community just on the basis of the Russian involvement in the hacking of institutions, tells me this will be a President who will disregard even the best assessments of the intelligence community when it doesn't suit his own version of events. That is extraordinarily damaging."
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CIA finding
US intelligence has previously linked Russia to leaks of damaging email from Democratic candidate Hillary Clinton's campaign but saw it as a broad bid to undermine confidence in the US political process.
On Friday, however, the Washington Post reported that the CIA has concluded that the aim of the cyber intrusions was to help Trump win the election.
The New York Times quoted a senior administration officials as saying there was "high confidence" that the Russians hacked both the Democratic and Republican National Committees, but leaked only documents damaging to Clinton through WikiLeaks.
WikiLeaks founder Julian Assange has denied links with Russia's government.
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Trump dismissed the reports as an attempt by Democrats to excuse their embarrassing election loss, asserting that US spy agencies were fighting among themselves and there is "great confusion" over the issue.
"Nobody really knows," he said. "They have no idea if it's Russia or China or somebody. It could be somebody sitting in a bed some place. They have no idea."
Trump suggested he had little confidence in the US intelligence agencies and would clean house once in office.
"We're going to have different people coming in because we have our people, they have their people. And I have great respect for them. But if you read the stories, the various stories, they're disputing. And certain groups don't necessarily agree."
Trump has kept the US intelligence community at arms length since his election, pointedly eschewing their daily briefing on world threats.
"I get it when I need it," he said.
"You know, I'm a smart person. I don't have to be told the same thing and the same words every single day for the next eight years. Could be eight years."
"I don't need that. But I do say if something should change, let us know."
Exxon chief for state?
Moscow's motives have drawn attention in part because Trump has often praised Russian President Vladimir Putin as a strong leader, and talked of working more closely with Russia to defeat the Islamic State group.
Rex Tillerson, said to be Trump's top choice for secretary of state, would bring to his cabinet a man with extensive business dealings with Russia as well as other problematic countries.
"In his case, he's much more than a business executive. He's a world class player," Trump said of Tillerson, a 64-year-old Texan who has run Exxon since 2006, making oil and gas deals worldwide.
"To me, a great advantage is he knows many of the players. And he knows them well. He does massive deals in Russia. He does massive deals for the company, not for himself," he said.
Raw nerve
On China, Trump touched a raw nerve by questioning whether the United States should continue its "one China policy" without concessions from Beijing on trade and other issues.
"I don't want China dictating to me," Trump said as he made a vehement defense of his recent phone conversation with the president of Taiwan.
"I don't know why we have to be bound by a one China policy unless we make a deal with China having to do with other things, including trade," he added in the interview on Fox News Sunday.
Since 1972, the United States has recognized that "there is but one China and that Taiwan is part of China."
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