The FBI is investigating the possibility of Russia being implicated in the recent hack of Democratic National Committee.
Fallout over the hack contributed to DNC Chairwoman Debbie Wasserman Schultz's resignation.
"The FBI is investigating a cyber intrusion involving the DNC and are working to determine the nature and scope of the matter," the agency said in a statement.
The suspected Russian hack is part of a wave of cyber attacks aimed at political organizations and academic think tanks.
Wikileaks began published documents released in the hack this weekend, but did not name a source.
The Hillary Clinton campaign put the blame on Russia immediately, saying that they intended to help GOP nominee Donald Trump.
The FBI has sent experts to meet with the Republican National Committee, as well as the major campaigns, to discuss their security measures, the officials say.