WASHINGTON — (CNN) The Democratic National Committee “rebuffed” a request from the FBI to examine its computer services after it was allegedly hacked by Russia during the 2016 election, a senior law enforcement official told CNN Thursday.

“The FBI repeatedly stressed to DNC officials the necessity of obtaining direct access to servers and data, only to be rebuffed until well after the initial compromise had been mitigated,” a senior law enforcement official told CNN. “This left the FBI no choice but to rely upon a third party for information. These actions caused significant delays and inhibited the FBI from addressing the intrusion earlier.”

This statement is in response to reports that the FBI never asked the DNC for access to the hacked systems.

The DNC told Buzzfeed News that they did not receive a request from the FBI to access their computer servers.

“The DNC had several meetings with representatives of the FBI’s Cyber Division and its Washington Field Office, the Department of Justice’s National Security Division, and US Attorney’s Offices, and it responded to a variety of requests for cooperation, but the FBI never requested access to the DNC’s computer servers,” Eric Walker, the DNC’s deputy communications director, told BuzzFeed News.

The FBI instead relied on the assessment from a third-party security company called CrowdStrIke.

The DNC did not immediately respond to a request for comment by CNN. But President-elect Donald Trump cited Thursday’s news to hit Democrats, tweeting, “So how and why are they so sure about hacking if they never even requested an examination of the computer servers? What is going on?”

Congress held hearings on the alleged Russia hacking on Thursday, where officials agreed on the conclusion that Russia is a major threat to the United States and was behind hacking meant to influence the outcome of the 2016 election.