Lindsey Graham, a senior US Republican senator, has said his campaign email account was hacked by Russians.
Sen Graham also told CNN he believed “the Russians hacked into” the Democratic National Committee.
And he accused Russia of trying to “destabilise democracy all over the world”, calling for a tough response.
President-elect Donald Trump earlier rejected a CIA assessment that Russian hackers tried to sway the 8 November election in his favour.
In a separate development, NBC News reported that US intelligence officials now believe with “a high level of confidence” that Russian President Vladimir Putin became personally involved in a covert Russian campaign to interfere in the US presidential election.
Russian officials have repeatedly denied the hacking accusations.
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