For weeks, the candidates for Illinois' open U.S. Senate seat have been repeating the old adage that the only poll that matters is the one held on election day.

The poll that matters arrived Tuesday.

Fifteen Republicans and Democrats vied to win their party's nomination and go on to replace retiring GOP Sen. Peter Fitzgerald (search) in a contest both national parties view as a key to determining control of the narrowly divided Senate.

The candidates' ads leading up to the primary have stayed away from attack ads and focused instead on issues ranging from health care to immigration.

But in the past three weeks, the release of one candidate's divorce records and the refusal of another to unseal his have seized the headlines, and several candidates have admitted using drugs during their college years.

Leading Republican Jack Ryan (search) largely shied away from the media spotlight in the final days of campaigning after Republican leaders and rivals began publicly urging him to unseal records in his divorce from actress Jeri Ryan ("Boston Public") — arguments that surfaced after Democrat Blair Hull released his own divorce records revealing he hit his former wife, sending his poll numbers plunging.

Ryan, an investment banker-turned-teacher and one of seven millionaires in the race, maintains the records are sealed to protect his 9-year-old son and has refused calls to let the state party chairwoman view the records so she can confirm they contain nothing damaging.

The latest statewide poll still showed Ryan leading the Republican field by a wide margin, however it was conducted early last week before Ryan's divorce became an issue.

Ryan was facing business executive Andy McKenna, dairy owner Jim Oberweis, state Sen. Steve Rauschenberger and four other candidates.

State Sen. Barack Obama (search), a Harvard-educated lawyer hoping to become only the fifth black U.S. senator, led among Democrats, followed by Dan Hynes, state's comptroller; Hull, a securities trader; and other Democrats in single digits.

Hynes, greeting voters at a cafe in Peoria, lamented that both parties' campaigns have been sidetracked by divorces and personal problems but predicted that the real issues would draw voters to the polls.

"The biggest factor is that the people of Illinois have had enough — they've had enough of job losses, they've had enough of George Bush giving us bad policies," he said.