During his presentation of Marquette Law's new poll in Wisconsin, poll director Charles Franklin made an interesting point: Nearly one-fifth of poll respondents in the state didn't have a preferred candidate between Donald Trump and Hillary Clinton, a number that Franklin dubbed "a huge percentage of the electorate." Why was it? Franklin had a hunch: The unpopularity of the candidates.

We've noted before that the "none-of-the-above" percentage of the electorate has been higher this year than in years past. As it stands, about 12 percent of the electorate doesn't have a preference between Clinton and Trump in the RealClearPolitics (RCP) national average -- a higher percentage than said the same at this point in 2012, 2008 or 2004.

There's a lot of variability there, including recently. But in 65 of the last 80 days, the percentage of the electorate that's not committed to a major-party candidate has been higher than it was on the same day relative to the election in the past three cycles. In Wisconsin, the edge is steeper. As it stands, without RCP factoring in Marquette, has 15 percent of the electorate shying away from the major-party candidates -- compared to 11 percent in 2008 and 5 percent in 2012.

It's hard to say how much of this is related to the unpopularity of the candidates. We know that both candidates are about equally unpopular right now, according to the most recent Post-ABC poll. Clinton saw some post-convention improvement in her favorability, but that's mostly evaporated. Women and white voters look at Clinton more unfavorably than they did before the conventions.

In our most recent poll from earlier this month, only 72 percent of voters who viewed both Trump and Clinton unfavorably had a choice between the two. Meaning that more than a quarter, 28 percent, fell into that none-of-the-above category. With more voters viewing the candidates negatively, it's safe to assume that more people therefore fall into that "no thanks" grouping. Eighty-eight percent of those who viewed both favorably -- not a lot of people -- had a preference.

Franklin followed up his comments about his poll with a question. Normally, as you can see in that first graph, people decide on candidates as Election Day approaches. So far, that's happened much more slowly this year than in years past. To what extent, Franklin wondered, will people continue to withhold support for the major-party candidates? He was referring to Wisconsin, but the idea holds more broadly. One on hand, it makes sense that third-party candidates could gain or voters could stay home -- a boon for Trump, given that Republicans tend to turn out more regularly than Democrats. But on the other hand, that dislike may spur people to go vote against candidates. In polling, Trump's base of support has consistently been made up mostly of people who were motivated by seeing Clinton lose, not seeing him win.

As with so many things this cycle, we may not have an answer to that question until Election Day.