Sen. Mitch McConnell, R-Ky., has been hospitalized for an unknown health issue, according to his office.

McConnell is the longest-serving Senate party leader in U.S. history.

He was in the hospital due to "flu-like symptoms" earlier in the year. 

"Sen. McConnell was admitted to the hospital this morning," McConnell's Communications Director David Popp said, according to Fox News. "He is receiving excellent care."