A police cruiser was parked outside the senator's home in West Miami, Fla., according to the Miami Herald, which first reported the news.

Neither law enforcement agency has commented on the report, but Rubio's office confirmed on Tuesday that the senator was the target of a threat, the Herald reported.

On Wednesday, Rubio is scheduled to deliver an address his office has billed as a "major speech" on foreign policy at the Brookings Institution in Washington.

Rubio, a Tea Party favorite, is seen as a possible vice presidential selection for presumptive GOP nominee Mitt Romney. The Florida lawmaker, however, has repeatedly said he has no interest in the position and would not accept an offer to join the ticket.