Could Third Party Candidates Prove Clinton's Achilles Heel?

Here's the good news for Hillary Clinton: Three new polls this week show the Democratic presidential nominee strengthening her lead over Republican rival Donald Trump.

The bad news: Two of those polls--and a chunk of others recently--show that when the Libertarian Party's Gary Johnson and the Green Party's Jill Stein are included in a theoretical match-up, Clinton's lead drops, making, according to a headline in Politico, a potential "third-party headache" for the former secretary of state.

A Fox News poll released Wednesday shows Clinton with a 10-point lead over Trump, 49-39 percent.

A McClatchy-Marist poll released Thursday also shows Clinton with a double-digit lead over Trump, 48-33 percent.

And an NBC News-Wall Street Journal poll, also released Thursday, shows Clinton with a 9-point lead over Trump, 47- 38 percent.

When the Fox News poll presented a three-way match-up to include the Libertarian Party, Johnson got 12 percent, Clinton 44 percent, and Trump 35 percent. That makes Clinton's lead over Trump 9 points, a one-point drop compared to the two-way match.

When the McClatchy-Marist poll presented a four-way match-up to include Johnson and Stein, Clinton still came out on top getting 45 percent to Trump's 31 percent, while Johnson has 10 percent and Stein 6 percent. This scenario also drops Clinton's lead over Trump by one point.

Politico's Steven Shepard writes that's it's a small, but consistent pattern.

In the 15 major national polls conducted since the first night of the Republican convention last month that included both the two-way and four-way ballot tests, Clinton has had a smaller lead over Trump in nine, and her lead has been unchanged in five of them. In only in one of the surveys has Clinton's lead actually increased when Johnson and Stein are included.

Shepard goes on to ask: "Why is Johnson (and Stein, for that matter) drawing more from Clinton when he is a former Republican in a year when Republicans are far more likely than Democrats to defect to the third-party candidates?"

"Young voters," he continues, though noting that another possible factor is that the pollsters present the question after they've asked about the two-candidate match-up, and that could artificially bump up support for third party candidates.

At the Washington Post, Aaron Blake takes a closer look at the McClatchy-Marist poll, which shows Trump "losing young voters not just to Johnson, but also to Green Party nominee Jill Stein," as he got just 9 percent of the vote from those under 30. Clinton, in contrast, still lead the pack at 41 percent, while Johnson had 23 percent and Stein 16 percent.

Johnson and Stein "might not beat Trump with this demographic, but they can surely do some real damage to his prospects of winning," Blake adds.

Further backing that up, a new GenForward survey found that the majority of the 18- to 30-year-olds polled have a negative view of both Clinton and Trump.

The BBC's Rajini Vaidyanathan says that this is an election season "when many voters are crying out for an alternative," noting that there are Republicans who won't support Trump as well as supporters of Bernie Sanders who say they won't support Clinton.

So it's not just young voters with a distaste for the leading candidates, as previous polls have shown. Indeed, as the Fox News poll shows, more voters view both Clinton and Trump as unfavorable than favorable.