A Russian cyberattack that targeted Democratic politicians was bigger than it first appeared and breached the private email accounts of more than 100 party officials and groups, officials with knowledge of the case said Wednesday. The widening scope of the attack has prompted the F.B.I. to broaden its investigation, and agents have begun notifying a long list of Democratic officials that the Russians may have breached their personal accounts. The main targets appear to have been the personal email accounts of Hillary Clinton’s campaign officials and party operatives, along with a number of party organizations. Officials have acknowledged that the Russian hackers gained access to the Democratic Congressional Campaign Committee, which is the fund-raising arm for House Democrats, and to the Democratic National Committee, including a D.N.C. voter analytics program used by Mrs. Clinton’s presidential campaign. But the hack now appears to have extended well beyond those groups, and organizations like the Democratic Governors’ Association may also have been affected, according to Democrats involved in the investigation.
Democrats say they are bracing for the possibility that another batch of damaging or embarrassing internal material could become public before the November presidential election.
The attack has already proved politically damaging. On the eve of the Democratic National Convention in Philadelphia last month, Representative Debbie Wasserman Schultz resigned as D.N.C. chairwoman after WikiLeaks released a trove of hacked internal emails showing party officials eager for Mrs. Clinton to win the nomination over Senator Bernie Sanders of Vermont.
American intelligence agencies have said they have “high confidence” that the attack was the work of Russian intelligence agencies. It has injected a heavy dose of international intrigue into an already chaotic presidential campaign as Democrats have alleged that the Russians are trying to help tilt the election toward the Republican nominee, Donald J. Trump.