Rep. Alan Nunnelee (R-Miss.) is resting comfortably after undergoing brain surgery on Monday, his office said in a brief statement. 

"His family is with him at the hospital and indicated that the surgery went well," according to the statement released Monday.  

The Mississippi congressman had the procedure to remove a small mass found on the right side of his brain. The tumor was isolated, according to a statement released last week

During a House Appropriations Committee hearing Tuesday, Chairman Hal Rogers (R-Ky.) said Nunnelee was in surgery for 12 hours, according to The Associated Press

The surgery took place at MD Anderson Cancer Center in Houston. He has not said how long his recovery is expected to take.