IOWA CITY, Iowa/NEW YORK (Reuters) - The 2016 election is shaping up to be the year of angry voters, the disgruntled Americans shaking up the establishment by fueling the presidential campaigns of two very different candidates - billionaire businessman Donald Trump and self-declared socialist Bernie Sanders.  Some 73 percent of voters likely to head to the polls in November’s election say they think the United States is on the wrong track, and these disaffected people make up a majority of the support bases for both Republican candidate Trump and Democratic hopeful Sanders - 87 percent and 54 percent, respectively, according to a Reuters/Ipsos poll. Both candidates were seen as long shots against brand name rivals like Jeb Bush and Hillary Clinton a few months ago, but have seen their popularity surge as the election race starts in earnest with the Iowa caucuses on Feb. 1. They are likely to do well in Iowa, but even if they lose, the fervor they’ve whipped up has upended the race and maybe even American politics. So who are the angry Americans? They deviate from the population in key ways: they are whiter, poorer and less educated. They are less likely to support a candidate who has been involved in politics. And regardless of party, they have deep distrust for Clinton after her more than two decades in the public eye. Where the camps differ is in identifying the root of America’s ills, with supporters of Sanders pointing to income inequality and health care as the top problems, and those backing Trump putting the blame on immigrants and foreign terrorists, according to the poll. Pundits have been quick to define the economy as the source of the voter anger feeding the Trump and Sanders campaigns. In a post-recession world, the middle class still struggles with stagnant wages and a weak job market. But a close look at the polls, and interviews with prospective voters, show concerns go well beyond economic indicators. Here in Iowa, the December jobs report issued Tuesday found just 3.4 percent unemployment – far below the national average and still on the decline. “Now Hiring” signs are ubiquitous across the state. Asked to select the top issue for the next president in the first 100 days of the new administration, 24 percent of voters nationwide who said the country was on the wrong track picked immigration - making it the most popular choice by that group.  Only 10 percent of those who think the nation is on the right track selected immigration, making it the fifth most popular choice for that group, according to the poll.  “Wrong track” voters were also more likely to say terrorism and the economy were concerns. Trump has built his campaign on an immigration platform that includes building a wall and deporting millions of undocumented immigrants. And his insistence that he could negotiate better trade deals provides a strong appeal to those concerned about disappearing jobs in a global economy. On Tuesday night in Iowa City, Trump’s rally drew both supporters and opponents. Eight times the event was interrupted by protesters, who were forced out of the packed gymnasium and heckled by the raucous crowd.  Jim Schmidt, 48, of Johnson County, Iowa, was among the angry. His 11-year-old son wore a button proclaiming “Bomb the shit out of ISIS. The child watched as protesters were ejected from the event, cheering and waving his hand in support. “I’m angry but I love it and enjoy it,” Schmidt said afterward. He’s backing Trump for his business experience and ability to bring about change.  Where Trump’s angry voters have been on display at rallies, the intensity around Sanders has manifested itself online - dominating message boards and comment sections. A liberal radio host in Oregon, Carl Wolfson, announced last month he was ending his show in part because of the vitriol coming from Sanders supporters. His Facebook post on the topic was then inundated with angry responses. Sanders is resonating among angry voters by focusing on income inequality, and promising to deliver universal health care and free college education. Meghan Metier, 22, of Iowa City said the Affordable Care Act - President Barack Obama’s signature healthcare reform - has allowed some of her friends to access Medicaid. But to keep it, she added, they have to be certain their income doesn’t exceed the poverty level, so they stay barely employed. For her the system is broken and Sanders is the only candidate who appears ready to fix it. “He’s a more reliable progressive,” she said, comparing him to Clinton.  (Editing by Richard Valdmanis and Mary Milliken) SAP is the sponsor of this coverage which is independently produced by the staff of Reuters News Agency.