(CNN) — Republican Sen. Lindsey Graham of South Carolina says the FBI is investigating a possible hack of his phone.

Graham said earlier this week his phone is “in the hands of the FBI” after someone apparently tried to hack his phone by impersonating Senate Majority Leader Chuck Schumer.

“So I get a message, I think, from Schumer. It ain’t from Schumer,” Graham said Wednesday at the Hill and Valley Forum, a tech event. “And next thing you know, my phone’s … Anything you can create apparently can be hacked.”

Taylor Reidy, a spokesperson for Graham, told CNN: “The [Senate] Sergeant at Arms is investigating a possible hack of Senator Graham’s phone.”

The FBI declined to comment.

A spokesperson for the Senate Sergeant at Arms, which investigates cyber threats to senators, did not respond to a request for comment.

Similar hacking attempts were reported on other Senate staff this week.

“Reports of a text-based phishing attack on Senate mobile devices are increasing,” states an email obtained by CNN that the Senate Sergeant at Arms sent Senate staffers on Monday. “The message impersonates a trusted source to start a conversation,” the Sergeant at Arms warned. The hacker then tries to get the target to install the Telegram messaging by clicking on a malicious link that “results in the device behaving abnormally,” the email states.

The incident with Graham, however, was on his personal phone, not a Senate device or Senate network, a source familiar with the matter told CNN.

It was not immediately clear who was behind the hacking attempt. Lawmakers and their staff face an array of cyber threats, from state-backed spies to cybercriminals.

One risk with hacking activity like what Graham experienced is that it is an attempt to gain broader access to targets in the Senate for future operations, the source said.

Hundreds of House and Senate staff, along with some lawmakers, had their sensitive personal information, such as Social Security numbers, stolen in a separate hack last year of a DC health insurance service.

This story has been updated with additional reporting.

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