'This Week' Transcript: Hillary Clinton, Sen. Bernie Sanders and Donald Trump

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ANNOUNCER: Starting right now on a special edition of This Week with George Stephanopoulos. It's on: with just one day to Iowa, the GOP contenders are in a fight to the finish. Frontrunner Donald Trump making his fiercest attacks yet.

DONALD TRUMP (R), PRESIDENTIAL CANDIDATE: Ted Cruz is an anchor baby in Canada.

ANNOUNCER: And as they chase Trump, Ted Cruz and Marco Rubio trade fire.

SEN. TED CRUZ (R-TX), PRESIDENTIAL CANDIDATE: A vote for Marco Rubio is a vote for amnesty.

SEN. MARCO RUBIO (R-FL), PRESIDENTIAL CANDIDATE: He's decided to run a very, you know, deceitful campaign.

ANNOUNCER: With the clock ticking down, we're one-on-one with Donald Trump.

Plus, 11th hour surprise. Hillary Clinton hit with that top secret email revelation. With Hillary and Bernie neck and neck in Iowa, could the new email firestorm put Sanders on top?

Clinton and Sanders join us live on This Week.

Trump, Clinton, Sanders, just hours until the first votes as we countdown to Iowa. From ABC News, a special edition of THIS WEEK. Here now, chief anchor George Stephanopoulos.

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GEORGE STEPHANOPOULOS, ABC HOST: Tomorrow night, we will know after a season of surprises with unconventional candidates riding a wave of anger with those first voters in Iowa just a few hundred thousand. Will they tell America's establishment we are through?

In these final hours, the candidates all across Iowa, Donald Trump rolls into Dubuque on his own Air Force One.

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TRUMP: Get out and caucus and don't stay back. I don't care if you're feeling horrible, you have 104 temperature, the doctor says you cannot leave it'll be the end of you if you leave bed, you cannot leave, you will not be able to make it, get out of bed and caucus.

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STEPHANOPOULOS: All three Clintons together in Cedar Rapids.

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HILLARY CLINTON (D), PRESIDENTIAL CANDIDATE: Thank you, Bill. Thank you, Chelsea. Thank you guys.

CHELSEA CLINTON, DAUGHTER OF HILLARY CLINTON: I am so proud to be my parents' daughter.

BILL CLINTON, 42ND PRESIDENT OF THE UNITED STATES: And you need a world class change maker. She is the best I've ever known.

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STEPHANOPOULOS: Ted Cruz called in Phil Robertson from Duck Dynasty.

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PHIL ROBERTSON, DUCK DYNASTY: Now Trump says he's not showing up for the debate with our man Cruz. Then let's call old Donald up and try to get him to do the debate.

(DUCK CALL)

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STEPHANOPOULOS: And listen to Bernie Sanders with the indie rockers Vampire Weekend.

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STEPHANOPOULOS: And now the pollster who knows Iowa best and writes the most has weighed in with her final numbers.

Ann Selzer's poll for the Des Moines Register and Bloomberg shows Donald Trump with a slight lead at 28 percent, Ted Cruz in second at 23. Marco Rubio at 15 and Ben Carson falling to 10 percent.

On the Democratic side, Hillary Clinton neck and neck with Bernie Sanders, holding a slim 3 point lead.

Let's dig into this now with Jon Karl in Des Moines. And Jon, let's start out with those Democrats right there. Bernie Sanders and Hillary Clinton so close right there, but they're drawing on completely different universes.