The Republican Party of Wisconsin said Thursday that hackers stole $2.3 million in funds that had been intended to support President Trump's reelection.
State party chairman Andrew Hitt said the theft was the result of "a sophisticated phishing attack" operation that included the use of doctored invoices purporting to be from vendors billing the party.
"These criminals exhibited a level of familiarity with state party operations at the end of the campaign to commit this crime. While a large sum of money was stolen, our operation is running at full capacity with all the resources deployed" to support the president's reelection bid, Hitt said.
The hack was discovered October 22 and reported to the FBI the next day, according to the party, which says no proprietary information appears to have been stolen.
The FBI did not immediately reply to a request for comment.
The Democratic Party of Wisconsin said it has also been targeted repeatedly by hackers but that it had warded off such attempts.
"According to our IT team, we've been the target of over 800 phishing attempts, with at least half of them seeking financial gains, all of which have been stopped and recorded in some form," Courtney Beyer, communications director for the Democratic Party of Wisconsin, said in a statement.
Federal officials have repeatedly warned of the potential for hackers to attempt to disrupt the November 3 election.
On Tuesday night, the Trump campaign website briefly appeared to have been hacked, displaying an anti-Trump message and a solicitation for cryptocurrency payments.
And on October 21, dozens of voters in a heavily Democratic county in Florida and across several other states received emails that purportedly came from a right-wing group that threatened to "come after" them unless they voted for President Trump. Officials in the states targeted in the scheme later said there was no evidence that any voter databases were breached.
Adam Brewster contributed reporting.