An old South Philly friend recently told me what Frank Rizzo and Hillary Clinton have in common. He had a serious point: Each was unable to build a large enough coalition of white, working-class voters to offset an opponent's monolithic minority vote.

W. Wilson Goode was the only man ever to defeat Rizzo in an election, and he did so by winning a huge proportion of the black vote. When Rizzo faced Goode in a Democratic primary in 1983, Goode won 98 percent of the city's black vote. Rizzo later changed his registration to Republican, and when the two squared off in the 1987 general election, Goode captured 97 percent of that same vote. Sen. Barack Obama, by comparison, consistently attracts black voters in the low 90s.

You could say Clinton lacks enough "bitter" voters in the national equivalent of South Philadelphia's 26th and 39th Wards to offset Obama's 20th (North Philly), 14th (Northern Liberties) and 27th (University City) Wards. Especially when combined with "elite" voters - the Society Hills and Rittenhouse Squares of the country.

In other words, Rizzo and Clinton found themselves so poorly supported among African American voters that they needed to win an impossibly high percentage of the white vote to prevail. Each found strength, albeit not enough, among non-college-educated, blue-collar whites, while their opponents put together a coalition of minorities and well-educated liberals.

Both also got into trouble with comments about the racial dynamics of their constituency. Consider Rizzo's experience on Sept. 21, 1978 - the defining moment of that campaign.

Rizzo himself wasn't running because the City's Home Rule Charter limited him to two successive terms in office. But he was pushing Philadelphians to vote to amend the charter and remove the term limitation.

Weeks before voters were to head to the polls, Rizzo addressed the Northeast Coalition for Community Problems. There he lamented that his opponents had urged blacks to "vote black." Those opponents - headlined by a united African American community - had boiled the charter change down to race.

Rizzo said: "I'm asking white people and blacks who think like me to vote like Frank Rizzo." He continued: "I say vote white." He added that "blacks who think like me, and there's a lot of them," should do likewise.

In that race, Rizzo secured only 34 percent of the vote. The city's African American wards voted against the charter change by 96 percent.

In the aftermath of the primaries in North Carolina and Indiana, Clinton sounded a bit like Rizzo when she told a USA Today reporter: "There was just an AP article posted that found how Sen. Obama's support among working, hard-working Americans, white Americans, is weakening again, and how the whites in both states who had not completed college were supporting me. And in independents, I was running even with him and doing even better with Democratic-leaning independents. I have a much broader base to build a winning coalition on."

She also said: "These are the people you have to win if you're a Democrat in sufficient numbers to actually win the election. Everybody knows that."

That sounds like the New Millennium version of Rizzo's 1978 pronouncement.

Both brought out legions of voters decidedly for or against them. Truly "undecided" voters in any contest where Rizzo's name appeared were as rare as such voters are with Clinton today. People tend either to really love, or to really hate, each of them. This despite numerous efforts by the two to reinvent themselves.

In fact, at one point Rizzo's 1983 ads proclaimed: "You don't have to like Frank Rizzo to vote for him as mayor." Clinton has similarly asked voters to seek out the larger cause, imploring us to decide - for the good of our children - that she is the candidate ready to answer the White House phone at 3 a.m.

Presumably, that is where the comparisons end. While both were Democrats, Rizzo changed parties late in his career. Then again, Clinton was raised a Goldwater Girl, and she recently has called for a temporary reduction in the federal gasoline tax. This after she has taken an increasingly hard line on Iran.

Hmmmm.

Michael Smerconish's column appears on Thursdays in the Daily News and on Sundays in Currents. He can be heard from 5 to 9 a.m. weekdays on "The Big Talker," WPHT-AM (1210). Contact him via the Web at http://www.mastalk.com.