CHICAGO —  Democratic Senate candidate Barack Obama (search) holds a commanding lead over his opponent with five months remaining until the November election, according to a poll released Monday.

Obama is supported by 52 percent of the state's registered voters while 30 percent favor Republican Jack Ryan (search), according to the first statewide Chicago Tribune/WGN-TV poll since the two won their primaries in March.

Both men are vying to replace Sen. Peter Fitzgerald, a Republican who decided not to seek re-election, citing a desire to spend more time with his family.

Twenty-five percent of voters surveyed for the poll viewed Ryan unfavorably, while Obama had an unfavorable rating of 9 percent.

Obama, who is black, also was found to have the support of 91 percent of black voters to just 4 percent for Ryan.

Ryan's campaign has been dogged by negative publicity concerning a video camera-toting aide who shadowed Obama's campaign. Ryan, a millionaire investment banker-turned-teacher, also faces the potential release of sealed court records from his divorce from actress Jeri Ryan.

The poll, conducted May 21-24, involved 600 registered Illinois voters and had a margin of sampling error of plus or minus 4 percentage points.