The Democratic National Committee has contacted the FBI after detecting what it believes to be a phishing attack in an attempt to hack into its voter database, CNN reported Wednesday.

The attack, which was discovered late Monday by a cybersecurity firm working for the DNC, took the form of a fake login page meant to appear identical to that of the service that hosts the database. It is believed to have been designed for hackers to steal login information to access the database. Two DNC officials also told the New York Times that the hackers had sent emails to people in the DNC to try to trick them into using the fake login page.

CNN reported that the DNC does not believe its voter files were accessed or in any way changed. The DNC said it is investigating who could have been behind the attack.

The spear-phishing attack—in this instance using emails to try to trick people into giving up sensitive information—is similar to the one used successfully to hack into Hillary Clinton’s campaign chairman John Podesta’s emails before the 2016 election.

In a statement to CNN, Bob Lord, the DNC’s chief of security, called the threats “serious” and blamed the Trump administration for not being more active in protecting U.S. elections and institutions from hacking. “It is their responsibility to protect our democracy from these types of attacks,” he said.

On Tuesday, Microsoft also announced that Russian hackers linked to military intelligence had used fake websites to target the U.S. Senate as well as conservative think tanks critical of Russia. Microsoft also said it believed it had caught the sites before any damage could be done. The group behind that hack was said to be the same one that hacked Podesta in 2016.

• Cybersecurity
• Democrats
• Election Security