The CBS2/SurveyUSA Poll conducted Friday and Saturday, before Keyes formally accepted the Republican nomination, showed the Maryland native trailing 67 percent to 28 percent. He was behind in all areas of the state -- even in the heavily Republican collar counties surrounding Chicago.
Obama led Keyes 62 percent to 34 percent in the GOP strongholds and was preferred downstate, 56 percent to 38 percent. Keyes led among Republicans 67 percent to 27 percent.
In Chicago, the poll found 79 percent support for Obama to 16 percent for Keyes, who signed a lease for an apartment in suburban Calumet City to establish Illinois residency.
Black voters favored Obama 89 percent to 10 percent and white voters favored the Democrat 62 percent to 32 percent. Both candidates are African-American.
Among women, it was 74 percent for Obama, 21 percent for Keyes.
Keyes Sunday replaced GOP nominee Jack Ryan, who withdrew because of a sex scandal.