In 2012, his own campaign's polls, among others, predicted Mitt Romney, the Republicans' nominee, would defeat President Barack Obama for the presidency, but just barely. Two years later, surveys in Kentucky strongly suggested then-Senate Minority Leader Mitch McConnell, perhaps the shrewdest, most powerful Republican in Washington, could lose his seat to an upstart rookie Democrat.

Overseas, meanwhile, multiple public-opinion experts in 2014 said Scottish voters were deadlocked on whether to scrap one of the oldest relationships in European history and choose full independence from Great Britain – and underdog nationalists' hopes soared.

Three different public-opinion polls, three important elections, three decisively erroneous results: President Barack Obama blindsided Romney in the 2012 presidential elections, winning a second term by five points; McConnell crushed Alison Lundergan Grimes en route to becoming Senate majority leader in 2014; and Scots last year overwhelmingly chose to keep ties with the United Kingdom, an outcome that stunned the polling establishment.

Once a seemingly infallible cornerstone of the political system, public opinion polls have racked up a few big-time fails in recent years, embarrassments that compelled a leading firm to conduct an internal audit to find out what went wrong. Analysts are also openly questioning whether the industry, whose leaders were household names in the 60s and 70s, has kept up with a rapidly transforming, highly-mobile electorate – one that's relying on everyday technology to opt out of the public discourse.

Others wonder if those factors combined to create the unlikely Summer of Trump, in which a boorish reality-TV billionaire with zero political experience and no apparent verbal filter shot past a dozen experienced politicians in 2015 presidential opinion polls to become the presidential front-runner, defying political gravity in the process. Or if skewed polls triggered the Hillary Slide, in which the likeability numbers of the Democrats' perpetual 2016 front-runner nosedived over several months, leading her campaign to plan more moments of spontaneity and reboot her warm, human side.

"The science of public surveying is in something of a crisis right now," says Geoffrey Skelley, a political analyst at the University of Virginia's Center for Politics.

And it matters because "polling is a very important element of democracy," said Michael Traugott, a University of Michigan political science professor who specializes in polling and opinion surveys. Traugott also helped prepare a groundbreaking report on how Gallup, a public-opinion titan, erroneously predicted Romney would defeat Obama in 2012.

Polls "give the public an independent voice that's not generally present" otherwise in politics and political news coverage, Traugott said. But he says the recent errors, and a steep decline in the number of people responding to opinion surveys, is "a worrisome trend because one of the main claims of polling is that it represents the people's views."

"I used to remember when survey conductors were celebrities," says Roger Tourangeau, an esteemed survey methodologist and vice president of the research firm Westat. "George Gallup and Lou Harris [of Harris Research Associates, an early industry giant] had columns in the newspaper" and would regularly appear on national TV.

"It's a different world now," he says.

In an unprecedented internal report on its 2012 Romney blunder, Gallup says it made mistakes in its core samples, including its racial makeup and political ideology, as well as its overall methodology.

Gallup's audit, however, also says the entire industry is due for an overhaul, with some of the leading firms using analog, black-and-white methods in a digital, multicultural world. Case in point: the rise of the cell phone and the fall of public engagement in opinion surveys.

Besides not being tied to a fixed address – it's not unusual for owners to have a different area code than where they actually live, and the numbers usually aren't listed in the white pages – cell phones provide more control over its users' privacy than a landline. It's likely, analysts say, that the ability to screen or block incoming calls has accelerated the public's unwillingness to take part in what used to be considered a civic duty.

"Everyone in the industry is worried about the falling response rate," Tourangeau says.

Traugott says the percentage at which people participate in opinion polls has bottomed out in the past few decades, from more than half in the 1980s to the single digits today, and most experts believe cellphone use is the reason.

Tourangeau says the technology factor likely slanted 2015 polls in Israel indicating embattled Israeli Prime Minister Benjamin Netanyahu's Likud Party was locked in a dead heat with the opposition just days before high-stakes parliamentary elections. Likud, however, won in a blowout, handing Netanyahu another term as Israel's leader and giving the polling industry another headache.

"It's not just an American problem. it's a worldwide problem," Tourangeau says.

At the same time in the U.S., a federal law designed to protect consumers from aggressive debt collectors or telemarketers bans pollsters from using automated calls to get opinions, even if it's on important issues like the presidential election or whether the nation's on the right track.

"People are leading more active lives, and they're harder to locate," Traugott says. People would rather text, make calls or perhaps play another round of Candy Crush Saga than spend up ten minutes or longer "for an interview with an organization they they might not know and a survey whose content might be unclear," he says.

Other factors, Tourangeau says: Gated, private communities that door-to-door surveyors can't reach, and more survey subjects who don't speak English as a first language.

Celinda Lake, a pollster, political consultant and president of Lake Research Partners, a Washington, D.C.-based polling firm, says polling has seen "kind of a steady decline. It's getting harder to reach people. It's also harder to get them to cooperate."

That means Lake Research, Gallup and others spend far more time, effort and money than ever before, trying to get solid opinions and deliver an accurate snapshot of the public mind.

"You try them more often. We've upped the number of callbacks; we used to do two or three. We now do three, four and five," Lake says. Sometimes, she adds, they even make appointments with survey subjects to get their participation.

But not every pollster has the time, the money, or a staff big enough, to up their game and dig into a major opinion survey with that level of commitment. That's especially true when campaigns, polling firms and news organizations are competing for attention in a hyper-speed, social media-fueled, 24-hour news environment, Lake says.

"That means there's getting to be a broader and broader range of quality of polls, where some people have the resources and some don't," Lake says. "And it makes for more variability" in across-the-board quality of results on a particular issue or political campaign.

Another key factor is polling firms' methodologies, the "secret sauce" of the industry, Traugott says. Put simply, if you ask the right sampling of people the wrong thing – questioning disengaged Virginia residents in 2014, for example, whether they prefer Rep. Eric Cantor, a veteran politician with wide name recognition, or Dave Brat, his unknown but more radical challenger, without determining if they'll actually show up to vote – you'll get a bad result.

Cantor, who had been one of House Speaker John Boehner's top lieutenants, learned that the hard way: he overestimated the polls, including his own campaign's, and didn't factor in a minimal primary turnout that gave Brat the slingshot he needed to slay a political Goliath. Instead of cruising to an easy win, Cantor fell hard, and Brat seized the seat Cantor held for 13 years.

Ultimately, Traugott and others say, the industry is responding with better methodology, improved modeling of public behavior, smarter ways to reach people (including Internet solicitations and small amounts of cash) and a commitment to learn from its mistakes. And they each said the industry as a whole nearly always gets it right.

"The trends are tough, Tourangeau says. "But it's not like the whole field has collapsed either. I'm not ready to give up on surveys at all."