For obvious reasons, I've lately been pondering examples from recent history where political nominees have proved too toxic for their own parties. There are more than a few examples—Tom Hayden, David Duke etc.—but only one with anything like contemporary resonance: The 1966 gubernatorial election in Maryland.

The Democratic primary that year was divided four ways, which enabled the least likely contender—a Baltimore paving contractor and perennial candidate named George P. Mahoney—to win the nomination with just 30 percent of the vote. Mahoney was a familiar, and unwelcome, figure to a majority of Maryland voters. And in the midst of the Great Society, his campaign's principal theme, which was opposition to open housing legislation, provided a catchy slogan ("Your Home is Your Castle") which delighted his longtime, indeed fervent, supporters, but embarrassed most Democrats. Among those Democrats were my very left-wing parents, whose memories of Mahoney-as-spoiler were long and distinctly unfavorable.

A half-century ago, Maryland was not quite so Democratic as it is today; but even then, Republicans running for statewide office faced an uphill struggle. Mahoney's openly racist campaign, however, provided an opening to the little-known, and essentially sacrificial, GOP nominee that year, Baltimore County Executive Spiro T. Agnew.

It is instructive to remember that, at this stage in his career, Agnew was regarded as a member of his party's progressive wing: A son of Greek immigrants with a liberal record on racial issues in suburban Baltimore County, and a supporter of Nelson Rockefeller for president. Positioning himself as the moderate alternative to Mahoney, more in tune with the times and temperament of border-state Maryland, was easily done. And Agnew was assisted by an infectious television campaign, featuring an earwigging theme song—"Your kind of man/ Ted Agnew is/ Taking your stand ...—set to the tune of "[Chicago is] My Kind of Town."

On Election Day, liberals such as my parents, horrified by the spectacle and prospect of George Mahoney, swallowed any partisan reservations they might have felt, and voted for the sensible alternative, Spiro T. Agnew. And of course, Agnew won. And 26 months later, he was a heartbeat away from the presidency.