Meet the GOP candidates for president -- all 15 of...

Meet the GOP candidates for president -- all 15 of them! Credit: Getty Images

The initial mistake by pundits early in the 2016 presidential race was to prematurely predict that campaigns by political outsiders -- non-establishment candidates -- would evaporate at a first gaffe or controversy.

Now, the same so-called experts ignore that a polling ceiling hangs over the same candidates that threatens any growth in their base of support.

The rise of businessman Donald Trump and retired neurosurgeon Ben Carson, not to mention Sen. Bernie Sanders' poll rankings, persistently flummox pundits. The presumption seems to be that if Trump and Carson each streaks toward a quarter of the polls in the Republican presidential primaries, it is a short leap for one of them to get close to the 50 percent needed in primaries to clinch a majority of delegates and the GOP nomination.

Similarly for Sanders, his appeal to progressive white voters is strong in early Democratic primaries, when the minority vote is minuscule. But unless he cracks into the large minority vote in later primaries, he will likely flare out much like Gene McCarthy, Morris King "Mo" Udall and Howard Dean did in earlier contests.

It would be wrong to ignore the high floor -- this primary base sustaining the Trump, Carson and Sanders candidacies. And it is equally foolhardy to ignore their low ceiling. The same polling that shows Trump in first place in some surveys also indicates he has the highest negatives in the Republican field and that about 60 percent of general election voters say they will not vote for him. Those negatives leave precious little space for Trump to grow once the large Republican field narrows.

Despite controversy over parts of his personal story, Carson's appeal is real -- anchored in the affinity Republican voters have for his persona and nonpolitical resume. Still, it's unclear whether that support will grow given his lack of experience in public policy.

Polls showing Sanders' appeal to liberal Democrats also reveal that he has precious little pull among moderate Democrats (which polling data by The Wall Street Journal shows is a full third of the Democratic primary electorate). Meanwhile, minority and moderate voters form a clear majority in later Democratic primaries.

Why primary voters are gravitating to anti-establishment candidates is not a mystery. The GOP's tea party wing seems to disparage any need for the Republican Congress to compromise with a Democratic president, while the Democrats' progressive flank is frustrated by the gridlock in Washington blocking governmental action.

Don't get me wrong, generating your partisan base is a prerequisite for winning the White House. Nevertheless, the mobilized Democratic base secures 45 to 46 percent of the national electorate while the flexed GOP base represents a 42 to 43 percent. That leaves a swing vote.

When that vital center of the electorate decides how it will vote next November -- to paraphrase Winston Churchill -- this electoral riddle wrapped in a mystery inside of an enigma will finally be solved.

Bruce N. Gyory, a political consultant at Manatt, Phelps & Phillips LLP, is an adjunct professor of political science at SUNY Albany.