Hillary Clinton and Bernie Sanders worked to expand their appeal Tuesday to voters who fueled President Barack Obama’s rise, while Republicans Donald Trump and Ted Cruz played up evangelical support ahead of the critical Iowa caucuses.

Six days before voting in the 2016 campaign kicks off, both parties were bracing for nail-biting caucuses in which either of the two front-runners could claim victory. Republicans were hoping Monday’s contest would help whittle down the field to make room for a more mainstream contender to challenge Trump and Cruz.

On the Democratic side, the race was hardening into a contest between Clinton’s vaunted resume versus Sanders’ judgment and world view. Clinton, in a new television ad, used archival footage of her from decades past to remind Iowans of her history as a battle-hardened champion for Democratic Party values.

"I’m Hillary Clinton, and I’ve always approved this message," Clinton said in a variation on the typical tagline.

Eyeing Obama’s upset victory in Iowa eight years earlier, both candidates sought to soak up the president’s good graces. Although Sanders has captured some of the energetic, status quo-busting aura of Obama’s campaign, he faces skepticism over whether he can turn out young voters and minorities as effectively as the president he’s running to succeed.

Asked whether he could match the historic turnout Obama secured in 2008, Sanders told a steel workers union in Des Moines that he hoped he could, but "frankly I don’t think we can. What Obama did in 2008 was extraordinary."

Still, with polls showing Sanders within a few points of Clinton, the Vermont independent waxed confident that he had an "excellent chance" to win Iowa. He predicted success in Iowa and New Hampshire would beget more support from party leaders who have firmly backed Clinton as the party’s best chance for a general election victory.

"I’m the candidate best able to do that, you can bet your bottom buck we’re going to have a whole lot of establishment Democrats on board," Sanders said in an Associated Press interview.

Clinton, who was crisscrossing northern Iowa for get-out-the-vote events, was savoring recent praise from Obama, who called her "wicked smart" and qualified to run the country from Day one. At a televised town hall forum Monday evening, she said she was "really touched and gratified" when she saw the interview — Obama’s strongest indication to date of his preference in the race. Obama isn’t expected to formally back a primary candidate.

Trump, riding high on a new poll showing his national lead growing, was deviating from his typical playbook by casting himself as a uniting figure able to work with Democrats if elected. He instead trained his attacks on Cruz, talking to morning TV shows to disparage Cruz as nervous and "such a mess."

Cruz appeared determined not to succumb to a war of words with Trump, whose supporters he’s working to peel off in Iowa and other early-voting states. Though lagging behind Trump nationally, Cruz is locked in a cutthroat race with Trump in Iowa as the broader Republican Party slowly comes around to the likelihood that one of the two could be their nominee.

"Donald has engaged in a lot of personal attacks," Cruz told reporters in Albia, Iowa. "I have not responded in kind, and I don’t intend to."

But the public comity aside, Cruz was working behind the scenes to undercut Trump’s claim to be a true conservative. Both Cruz’s campaign and a super PAC backing him were airing new ads accusing Trump of supporting abortion rights.

Perry, who ended his second presidential bid in September, said he knew Cruz previously through "the caricature of the media," but had gotten to know him better since dropping out.

"He may be one of the great listeners I’ve ever been around in my life," Perry said.

Both Cruz and Trump are seeking to capitalize on a strain in the GOP hungry for an insurgent conservative that can shake up the status quo. Trump spent the morning playing up an endorsement from Jerry Falwell Jr., president the Liberty University and an influential voice in evangelical politics.

Marco Rubio, hoping his recent gains in Iowa would continue, secured the endorsement of George Pataki, who also dropped out of the race last year. In New Hampshire, John Kasich was touting recent endorsements from the Boston Globe and Concord Monitor, while Chris Christie sought to capitalize on his nod from the Boston Herald.

(Copyright (c) 2016 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

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