Donald Trump is trailing Hillary Clinton on an array of major issues...and just barely beating her in Missouri, according to a new poll. And surveys may be overstating support for third-party candidates. This is HuffPollster for Wednesday, August 24, 2016.

VOTERS TRUST CLINTON MORE THAN TRUMP ON MAJOR ISSUES - Samantha Neal: “More voters trust Hillary Clinton than Donald Trump on nearly every key issue ― a feat not achieved by any candidate in recent elections, according to polling data aggregated by The Huffington Post. Trump trails Clinton in voter trust on each of the issues that typically rank highest in people’s minds when evaluating a presidential candidate ― the economy, immigration, terrorism, national security, foreign policy, social issues and criminal justice...Improving national security and tackling terrorism are central tenets of Trump’s campaign, and are issues that both Bush and McCain won by decisive margins during their electoral bids. In this election, however, Clinton leads Trump on the issue by an average of 2.1 percentage points.” [HuffPost]

AMERICANS HAVE HIGHER DEBATE EXPECTATIONS FOR CLINTON - HuffPollster: “Americans expect Hillary Clinton to do a better job than Donald Trump in the presidential debates this year, according to a new HuffPost/YouGov poll. By a 10-point margin – 45 percent to 35 percent – Americans think Clinton will outperform Trump, while another 20 percent aren’t sure.Democrats are somewhat more confident in their nominee than Republicans are ― 86 percent of Democrats expect Clinton to prevail, while just 73 percent of Republicans say the same of Trump. Independents are split about evenly between the two candidates….Twenty-one percent of Americans agree with the current [debate] ground rules, saying they’d like to see third-party candidates who meet the polling threshold included, while 31 percent want to see third-party candidates included regardless of how well they’re doing in the polls. Another 33 percent only want Clinton and Trump to be included.” [HuffPost]

THE RACE COULD BE TIGHTENING IN MISSOURI - Arthur Delaney: “Hillary Clinton is essentially tied with Donald Trump in red-tinted Missouri, according to a new poll. Clinton garners 43 percent support to Trump’s 44 percent among likely Missouri voters in a Monmouth University poll that has a margin of error of 4.9 percent. While the survey is strikingly bad news for Trump ― Missouri went for the Republican in each of the past four presidential contests ― it’s just one survey. Others show Trump ahead, and HuffPost Pollster tracking shows the conspiracy theorist-in-chief maintaining his advantage in the state…. Republican nominee Mitt Romney comfortably defeated President Barack Obama in Missouri in 2012, but John McCain barely defeated Obama there in 2008.” [HuffPost]

JILL STEIN PULLS SUPPORT FROM CLINTON, WHILE GARY JOHNSON AFFECTS BOTH CLINTON AND TRUMP - Mark Blumenthal: “Throughout 2016, pollsters have debated the best way to measure support for third party candidates.Some vote choice questions include Libertarian Gary Johnson and Green Party candidate Jill Stein as explicit options, some do not, and often the results vary accordingly…. In this week’s survey, Hillary Clinton leads Donald Trump by an eight-point margin, 50 to 42 percent, when we ask voters to choose between them….This week, when we include Johnson and Stein among the choices, Clinton’s lead over Trump narrows to five percentage points (43 to 38 percent), while Johnson and Stein receive 11 and 5 percent of the vote respectively. Clinton’s margin shrinks because those who choose Jill Stein on the four-way question opt overwhelmingly for Clinton when matched only against Trump.” [SurveyMonkey]

But voters might be overstating their support for alternative candidates - More from Blumenthal: “Earlier this summer, SurveyMonkey conducted an experiment which generally confirms that prompting for Johnson and Stein overstates their support. In early June, we split our sample into random thirds, offering voters either the two-way or four-way vote questions, or a third alternative that asked voters to choose between Clinton, Trump or ‘another candidate.’ Those that opted for ‘another’ were prompted to ‘specify’ their preference by typing it in. Results for the two and four way questions were similar to current voter preferences…. When offered an unnamed alternative, 20 percent opted for ‘another’ candidate, yet when we examined specific preferences just 2 percent had typed in Johnson or the Libertarian Party and just 1 percent typed Stein or the Green Party. More than twice as many (7 percent) typed in Bernie Sanders, who was still an active candidate at the time.” [SurveyMonkey]

TRUMP’S CAMPAIGN MANAGER SAYS ‘UNDERCOVER VOTERS’ WILL SUPPORT HIM - Ben Jacobs and Oscar Rickett: “Trump’s campaign manager Kellyanne Conway outlined her vision of how the Republican nominee could win in November despite consistently trailing in polls, during an interview with Channel 4 in the United Kingdom for the documentary President Trump: Can He Really Win? Conway insisted that Trump’s support was not reflected in polls because of the perceived social stigma of supporting the Republican nominee. ‘Donald Trump performs consistently better in online polling where a human being is not talking to another human being about what he or she may do in the elections … it’s become socially desirable, especially if you’re a college educated person in the US, to say that you’re against Donald Trump,’ said Conway.” [Guardian]

The only problem? Trump isn’t actually performing better in polls without a live caller, as we wrote earlier this month. [HuffPost]

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WEDNESDAY’S ‘OUTLIERS’ - Links to the best of news at the intersection of polling, politics and political data:

-Conspiracy theorists are going after Monmouth University’s poll director. [Politico]

-Asma Khalid investigates why Colorado favors Clinton in this election. [Colorado Public Radio]

-Political scientists weigh in on the GOP’s chances of keeping their majorities in Congress. [Vox]

-Frank Newport notes the common ground between Clinton and Trump’s economic plans. [Gallup]

-Kathleen Searles, Martha Humphries Ginn and Jonathan Nickens find that TV news is more likely to report on polls showing a close race or a major shift. [WashPost]

-Nate Silver calls for an end to arguments about the unusual methodology of the USC/LA Times’ tracking poll. [538]