>>> WHEN CHICAGOANS GO TO THE POLLS TO PICK A NEW MAYOR AND ALTAR PERSON THEY WON'T SEE THE LETTERS R OR D. THE CITY HAS LONG BEEN A DEMOCRATIC STRONGHOLD AND A REPUBLICAN HASN'T BEEN MAYOR FOR NEARLY A CENTURY, CHICAGO HAS HELD NONPARTISAN ELECTIONS SINCE 1999.

HEATHER IS HERE TO TELL US WHAT PROMPTED THAT CHANGE.

>> Reporter: IT MAY BE A CLICH÷ BUT THERE IS TRUTH AT THE HEART OF THE OLD SAYING THAT CHICAGO POLITICS IS A WARNING THAT THE FAINT OF HEART SHOULD HEED.

THE POWERS THAT BE DID NOT TAKE THAT DEFEAT LYING DOWN.

IF THEY COULDN'T BEAT CANDIDATES LIKE WASHINGTON, THEY WOULD MOVE THE GOALPOST.

OUR LATEST ADDITION OF WTTW NEWS EXPLAINS DETAILS WHICH PROMPTED THAT CHANGE MORE THAN TWO DECADES AGO AND WHAT IT TELLS US ABOUT CHICAGO POLITICS TODAY.

WHEN CHICAGOANS GO TO THE POLLS TO VOTE FOR MAYOR, THERE'S A CRUCIAL PIECE OF INFORMATION MISSING FROM THEIR BALLOT.

THE CANDIDATE POLITICAL PARTY.

WE HAVE HELD NONPARTISAN ELECTION SINCE 1999.

THE TOP TO HEAD TO A RUNOFF A MONTH LATER REGARDLESS OF THEIR POLITICAL AFFILIATION.

SO WHY THE CHANGE?

WE TAKE YOU TO THE RACIALLY CHARGED 1983 ELECTION FOR MAYOR.

IN THE BLUE CORNER, ATTEMPTING TO BECOME THE CITY'S FIRST BLACK MAYOR, HAROLD WASHINGTON.

IN THE RED CORNER BERNIE WITH HIS INFAMOUS SLOGAN , BEFORE IT'S TOO LATE.

WASHINGTON WON THAT ELECTION BUT JUST BARELY WITH LESS THAN 52% OF THE VOTES.

BY COMPARISON, FOUR YEARS EARLIER JAMES BYRNE RECEIVED A WHOPPING 82% OVER HER REPUBLICAN OPPONENT.

IN THE PRIMARY WASHINGTON WENT TOE TO TOE WITH BURN AND RICHARD M DALEY WHO SPLIT THE WHITE VOTE GRANTING WASHINGTON AND NARROW VICTORY AND HIS SPOT AS THE DEMOCRATIC NOMINEE.

THE CURRENT RUNOFF SYSTEM WOULD HAVE PIT WASHINGTON AGAINST BARN.

INSTEAD HE FACED THE RELATIVELY UNKNOWN AND REPUBLICAN BUT WHITE EPSON AND JUST BARELY CLINCHED A WIN.

STILL, WASHINGTON DID WIN.

SO WHITE CHICAGO POLITICAL LEADERS TOOK A PAGE FROM SOUTHERN STATES USING RUNOFF TO KEEP BLACK CANDIDATES FROM WINNING.

IN 1995 WITH THE SUPPORT OF THEN MAYOR RICHARD M DALEY AND A REPUBLICAN CONTROLLED STATE GOVERNMENT, THE CURRENT NONPARTISAN SYSTEM WAS PUT IN PLACE.

IF REPUBLICANS THOUGHT THE CHANGE WOULD BOOST THEIR CHANCES, THEY HAVE BEEN UTTERLY DISAPPOINTED.

THE LAST MEMBER OF THE GOP TO BE ELECTED MAYOR OF CHICAGO WAS BILL THOMPSON IN 1927.

BUT IN POLITICS, HOPE SPRINGS ETERNAL EVEN IF YOU HAVE TO CHANGE THE RULES TO TRY AND WIN THE GAME.

>> WE ALL REMEMBER THE BIG BILL THOMPSON ERA IN CHICAGO POLITICS.

THE IDEA IS A RUNOFF WOULD HELP PROTECT CANDIDATES AS LONG AS THE CANDIDATE FINISHED FIRST OR SECOND IN THE INITIAL ROUND OF VOTING.

>> Reporter: EXACTLY.

THIS WAS THE POLITICAL CALCULUS THAT THE VICTORY OF HAROLD WASHINGTON CHANGED.

HE WAS THE FIRST BLACK MAYOR OF CHICAGO AND HE BROUGHT OUT HUNDREDS OF THOUSANDS OF BLACK CHICAGOANS TO REGISTER TO VOTE AND CAST THEIR BALLOTS.

THAT MADE IT IMPOSSIBLE FOR THE DALEY MACHINE TO OPERATE THE WAY IT WANTED.

>> EVEN WITH THE ELECTION BEING NONPARTISAN, THE ISSUE OF PARTY AFFILIATION STILL COMES UP FROM TIME TO TIME, DOESN'T IT?

>> Reporter: IT HAS BEEN FRONT AND CENTER IN THIS RACE WITH LORI LIGHTFOOT TRYING TO CONVINCE VOTERS THAT PAUL VALLAS IS ACTUALLY A REPUBLICAN AT HEART IF NOT IN NAME.

>> SHE IS TRYING TO PAINT PAUL VALLAS AS A REPUBLICAN AND SHE SAID SHE WOULD LIKE TO FACE PAUL VALLAS IF THE CONTEST GOES TO A RUNOFF.

WHY IS SHE SAYING THAT?

LET'S LISTEN TO WHAT SHE TOLD REPORTERS.

>> I WOULD LOVE TO HAVE PAUL VALLAS AS MY RUNOFF CHALLENGER.

THAT IS AN IDEAL MATCHUP FOR US.

>> I HAVE MY OWN IDEAS BUT WHY DOES SHE WANT TO FACE VALLAS OF ALL THE CANDIDATES?

>> Reporter: SHE THINKS SHE CAN BEAT HIM IN A HEAD-TO-HEAD CONTEST.

SHE WOULD BE THE MORE PROGRESSIVE CANDIDATE AND SHE THINKS THAT WOULD GIVE HER AN ADVANTAGE OVER VALLAS WHO HAS TAKEN CONSERVATIVE POSITIONS AND ACCEPTED THE ENDORSEMENT OF THE CHICAGO POLICE UNION WHOSE LEADER IS A TRUMP SUPPORTER.

VALLAS IS A DEMOCRAT AND HAS RUN IN MANY ELECTIONS AS A DEMOCRAT.

PAT QUINN'S RUNNING MATE SEVERAL YEARS AGO SO WHAT ARE SOME OF THESE POSITIONS OUTSIDE THAT NEEDS TO BE TAKEN.

>> Reporter: HE GOT HIS START IN CHICAGO POLITICS AS HEAD OF THE CHICAGO PUBLIC SCHOOLS AND HE TURNED THAT INTO A CAREER AS A SCHOOL TURNAROUND EXPERT AND HE PUSHED CHARTERS, PRIVATIZATION EFFORTS AND FAVOR THE USE OF VOUCHERS WHICH WOULD GIVE PARENTS PUBLIC MONEY TO SEND THEIR KIDS TO PRIVATE SCHOOL.

>> THERE IS ONE CANDIDATE IN THIS RACE THAT PUBLICLY DECLARES HE IS NEITHER REPUBLICAN NOR DEMOCRAT.

WHO IS THAT?

>> Reporter: WILLIE WILSON.

EVEN THOUGH HE RAN FOR PRESIDENT IN 2016 AS A DEMOCRAT AND THEN VOTED FOR DONALD TRUMP IN 2016, HE SAID HE IS NEITHER DEMOCRAT NOR REPUBLICAN.

WHEN HE RAN FOR U.S. SENATE A FEW YEARS AGO HE WAS A MEMBER OF THE WILLIE WILSON PARTY.

>> I THINK THAT IS A PARTY THAT HAS A MEMBERSHIP OF ONE AT THIS