Social media accounts associated with Sen. Joe Manchin's office were hacked, the West Virginia Democrat announced on Thursday.
A news release from Manchin's office said the accounts have "since been secured." The extent of the hacking and when it took place were not immediately clear.
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"Manchin and staff are working with state and federal law enforcement officials to prevent further hacking and secure all accounts," the statement from Manchin's office added.
Manchin's office did not immediately return CNN's request for additional information.
The revelation comes days before voters head to the polls for the midterm elections -- the first major US election since 2016, when the US has accused Russia of interfering in the electoral process.
Manchin is being challenged by Republican Patrick Morrisey, the state's attorney general, and President Donald Trump is scheduled to stump in Huntington, West Virginia, on Friday -- an area where Trump won 60% of the vote in 2016. Despite being a Democrat in Trump country, Manchin is favored to win.
Manchin isn't the first member of Congress to report that their office has been targeted by hackers. In July, Sen. Claire McCaskill said Russians had unsuccessfully attempted to hack her Senate computer network.
"While this attack was not successful, it is outrageous that they think they can get away with this," the Missouri Democrat said at the time in a statement. "I will not be intimidated. I've said it before and I will say it again, (Russian President Vladimir) Putin is a thug and a bully."
Her statement was in response to a report by The Daily Beast, which said hackers had sent forged emails to targets in the Senate with malicious links as part of an effort that Microsoft picked up. The tactic resembled the successful phishing attack against John Podesta, Hillary Clinton's campaign chairman in the 2016 presidential election, according to The Daily Beast's July report.
At the Aspen Security Forum in July, Microsoft executive Tom Burt said Russian intelligence operatives had attempted to hack three 2018 campaigns.