The network said two unidentified congressional sources said the 65-year-old doesn't want to serve out the rest of his term.
In August, the former high school teacher said he wouldn't seek re-election in 2008.
"I think he is just done with being a member of Congress," a Republican aide told CNN.
Hastert was elected speaker in 1999 after 12 years in Congress but lost the position last November when Democrats took the majority in midterm elections. In 2003, Republicans waived term-limit restrictions to allow him to retain the speaker's role.
A total of 13 Republican House members have said they won't seek re-election in 2008.