The social media accounts associated with Sen. Joe Manchin's office have been hacked, his office announced Thursday.
A statement from his office said he was notified of the hack on Thursday, and the accounts have since been secured. The West Virginia Democrat and his staff are working with state and federal law enforcement to prevent further hacks, his office said.
It's unclear who is behind the hack.
Manchin is fighting to keep his Senate seat away from Republican challenger Patrick Morrisey in next week's midterm elections. President Trump is holding a campaign rally for Morrisey and other Republicans in West Virginia Friday afternoon.
Manchin's office isn't the first to be targeted by hackers. Russians have targeted Sen. Claire McCaskill's office,. McCaskill is another vulnerable Democrat in Tuesday's midterm elections.
"While this attack was not successful, it is outrageous that they think they can get away with this," McCaskill said at the time. "I will not be intimidated. I've said it before and I will say it again, Putin is a thug and a bully."
Sen. Ron Wyden, a Democrat from Oregon, warned his colleagues in September that the state-backed Russian group behind the 2016 Democratic National Committee hacking has also tried to hack the networks of senators and staffers.
Manchin, a moderate Democrat, was the only one to vote in favor of Supreme Court Justice Brett Kavanaugh. But that hasn't kept the president from campaigning against him. Still, Manchin has at times spoken favorably of the president in the state that voted for Mr. Trump by the largest margin in 2016.
"Our president -- whether you voted for him or not he's the president of the United States -- I want him to succeed and do well. And I'll stand up and support him when it's good for West Virginia -- and when it's not, I stand up to him," Manchin said in a debate with Morrisey Thursday night.