Conservative talk show host Rush Limbaugh remained hospitalized in Hawaii on Thursday after experiencing chest pains, according to the guest host on his nationally syndicated radio show.

Limbaugh, 58, was rushed to a Honolulu hospital Wednesday during a vacation.

Guest host Walter E. Williams described Limbaugh's pains as similar to a "heart attack coming on." But Williams said doctors haven't confirmed whether he had a heart attack; more exams were planned Thursday.

"Rush continues to rest very comfortably in a hospital in Honolulu this afternoon," Williams said. "He had a comfortable night, and he's getting good medical attention."

Williams, an economics professor at George Mason University, was already set to fill in Thursday while Limbaugh was on vacation.

Kit Carson, Limbaugh's chief of staff, said Limbaugh was due to return to his show Monday. He didn't know whether that schedule would change.

Update

Fans call in to show with get-well messages. To see the story, click here.