If Iowa voters are any indication, 2016 may be shaping up as the year that angry voters coalesce on their gripes more than any single candidate.

Responses from Republicans and Democrats who described themselves as likely to attend next year's first-in-the-nation caucuses in the latest Bloomberg Politics/Des Moines RegisterIowa Poll reveal a strong level of bipartisan discontentment over the state of American politics. When asked to assess their feeling about "politicians in general," just 7 percent of Republicans and 16 percent of Democrats said they were either "happy" or "satisfied." By contrast, 91 percent of Republicans and 82 percent of Democrats surveyed said they were either "unsatisfied" or "mad as hell" about politicians.

Those figures help explain the strong showing in the polls for billionaire real estate developer Donald Trump, retired neurosurgeon Ben Carson and socialist Vermont Senator Bernie Sanders, three candidates who have all pitched themselves to voters as either political outsiders or alternatives to the mainstream.

In the Democratic primary, the poll released Saturday showed Sanders having gained significant ground on front-runner Hillary Clinton, with 30 percent of support from likely caucus- goes for Sanders as compared to Clinton's 37 percent. Back in May, Sanders was at just 16 percent and Clinton was at 57 percent. Appearing Sunday on CNN's State of the Union, Sanders claimed the poll reflects momentum in the early-nominating states and beyond.

"Not only in Iowa, not only in New Hampshire, but all over this country we're generating enormous enthusiasm," Sanders said.

And it's not just Sanders sees this poll as a possible harbinger of bigger things. Pollster J. Ann Selzer, who conducted the survey for Bloomberg and the Register, appeared on CBS's Face the Nation, noting that there were some important firsts in the poll.

"Well, I think the first thing that jumps right off the page is this is the first time in Iowa that we’ve seen Hillary Clinton below fifty percent. And she’s not just a little below fifty percent, she’s lost a third of her support since June," Selzer said.

She added that, while Sanders is seven points behind overall, he's already leading with the coalition that cost Clinton her last nomination bid.

"[Sanders] leads by eight points with people who say this is the first time they’ll participate in the caucus," Selzer said. "He leads by over twenty points with people who say they consider themselves independent, and people who are under age 45. Now that’s the Obama coalition. Those are the groups that he put together that surprised Hillary Clinton in 2008."

One likely caucus goer, Mindy Johnson, 37, a hospital lab technician from Woodbury County, chose Sanders as a first choice in the poll, but she wasn't completely fired up and feeling the Bern.

"The other options aren't that great," Johnson said, adding that what she really wanted was for Massachusetts Senator Elizabeth Warren to run. That said, Johnson said she found Sanders's outsider status appealing.

"I think he seems like he's a little bit more against big business and a little bit more for social programs," Johnson said. "He doesn't seem like he's part of the system."

Over at the political roundtable on ABC's This Week,Associated Press reporter Julie Pace noticed the same parallel.

"It's really fascinating, this Iowa poll, the latest poll out of Iowa shows that Sanders is picking up support from the people who voted for Barack Obama in 2008 when he defeated Hillary Clinton in Iowa," Pace said. "The question for Sanders is going to be, could he take these young people, people who haven't caucused previously, and have a lot of enthusiasm for his message, and turn them in caucus-goers?"

A separate Bloomberg Politics/Des Moines Register poll of likely Republican caucus-goers still had Donald Trump leading with 23 percent, but Ben Carson was creeping closer to him, with 18 percent.

Once again, poll participants favored the perceived outsiders. According to one participant, Patrick Messmore, a 32- year-old salesman from Black Hawk County, that's no accident. Messmore said Trump is his first choice and that either Carson or Ted Cruz were good second choices. In the poll, Messmore chose Cruz as a second choice. Trump's newcomer status is a big part of his appeal, Messmore said.

"I think the biggest thing is his kind of no nonsense approach to everything and he's not a lifetime politician," Messmore said. "He's offering the things that everyone else is afraid of offering. Right now I guess he's my number one pick but Ben Carson's a really good candidate, too."

Scott Walker, a one-time potential frontrunner, on Sunday said he does not expect this to be the end of the story, that he's been here before, and that he expects his performance to improve.

"Well, you know, four years ago, I was so low in the polls they called me 'Dead Man Walker,'" Walker said, appearing on NBC's Meet the Press."A year later, I won the recall with a higher percentage of votes, a higher number of votes."

For his part, Carson retweeted Bloomberg Politics and the poll: