Police investigating threats against Marco Rubio The U.S. Capitol Police confirmed Wednesday that they are working with law enforcement agencies in Miami to investigate a threat against Sen. Marco Rubio (R-Fla.). (Haraz N. Ghanbari - AP) The Florida senator, who gave a major speech on foreign policy at the Brookings Institution on Wednesday, is among the Republicans believed to be under consideration to serve as Mitt Romney's vice presidential running mate. Rubio campaigned with Romney in Pennsylvania this week, fueling the speculation that he is under consideration. "We don't comment on security," said Rubio spokesman Alex Conant, who referred reporters to the U.S. Capitol Police. In an e-mail, Lt. Kimberly Schneider, a Capitol Police spokeswoman, said her agency "is working with local law enforcement in Miami." "USCP currently has an active, open investigation regarding the report of a threat against Sen. Rubio," Schneider said. We do not discuss the security of Members of Congress. The Miami Herald first reported Wednesday that the unspecified threat against Rubio was deemed credible enough as to merit police protection in Washington and outside the senator's home in West Miami. The Herald said a police cruiser was parked in front of Rubio's home Tuesday night. Napolitano: Secret Service probe will "leave no stone unturned" Hillary Clinton's record popularity The Fix: Obama is cool. Romney is not.