Maryland Gov. Larry Hogan (R) announced in a press conference Monday afternoon that he has been diagnosed with a late stage 3 non-Hodgkin’s lymphoma — a cancer he described as “very advanced and very aggressive.”

The governor said he will remain in office while he undergoes treatment.

Well-wishes started pouring in for Hogan, including a statement from his predecessor, former Maryland governor and Democratic presidential hopeful Martin O’Malley.

“Katie and I are very saddened by this news,” O’Malley said in a statement. “We send our thoughts and prayers to Governor Hogan’s family during this difficult time, and wish him the best in overcoming this challenge.”

Other officials, from former Democratic Lt. Governor Anthony Brown — whom Hogan upset this past November in deep-blue Maryland — to U.S. House Speaker John Boehner (R-Ohio), sent messages to Hogan on Twitter, as did many Maryland residents.