We begin with that shakeup in the 2016 race, a brand-new poll coming in overnight from the critical state of Iowa. Showing senator Bernie sanders closing in on Hillary Clinton. While on the republican... See More
We begin with that shakeup in the 2016 race, a brand-new poll coming in overnight from the critical state of Iowa. Showing senator Bernie sanders closing in on Hillary Clinton. While on the republican side, Donald Trump is still soaring. It's "Your voice, your vote," and let's take a look at those Numbers. Among republicans, trump leads, followed by another outsider, Dr. Ben Carson, then nobody else breaks double digits. Ted Cruz and Scott walker are tied for third. But trailing far behind trump. The biggest surprise is among democrats, Clinton's lead, now, down to single digits, just seven points ahead of sanders. It's the first time she's dropped below 50% in "The des Moines register"/bloomberg poll this year. We're taking on every twist and turn in the 2016 race this morning and Bernie sanders is standing by live to weigh in. First, ABC's Jon Karl on the dramatic difference between the leading candidates right now. Reporter: It's the tale of two front-runners. For one, the best of times. For the other, well, it's not the worst, it's getting there. The republican establishment fretting their front-runner is too strong could actually win. Democratic establishment fretting theirs is still weak and could lose. As Hillary Clinton has a comfortable lead in national polls, she's already trailing a 73-year-old self-described socialist in New Hampshire and now Bernie sanders is surging in Iowa as well. Despite yet another mea culpa over her home e-mail server. I should have used two e-mails, one personal and one for work, and I take responsibility for that decision. Reporter: Doubts over her e-mail account still under investigation by the FBI are taking a toll. 61% of voters now say she's untrustworthy. While some democrats are urging vice president Biden to jump in, handing out these candy bars at this week's dnc meeting. Trump, meanwhile, is having the time of his life, riding high in the early states, riding high nationally. Seemingly riding high everywhere. Top republicans worry he's alienating key voting groups. Jeb bush even making his own trip to the border to trash trump's plan to deport undocumented immigrants. His proposal is unrealistic, it will cost hundreds of billions of dollars. It will violate people's civil liberties. Reporter: But perhaps the biggest attack on the front-runners come are not from their supporters but the voters. First words to come to mind about each of them. For Hillary Clinton -- liar, dishonest, untrustworthy. For Donald Trump, arrogant, blowhard. So much for great expectations for either front-runner. For "This week," Jonathan Karl, ABC news, Washington.
This transcript has been automatically generated and may not be 100% accurate.