DES MOINES — Eight years ago, Barack Obama delivered a speech that rocketed his unlikely campaign to victory in Iowa, setting his course to the nomination, the election, reelection, and his two-term legacy in the White House.

Here on Saturday night, on the same stage at the Jefferson-Jackson Dinner, the annual state party fundraiser, Obama appeared only briefly and in pixelated form, by way of a video message to the crowd. But the candidates hoping to replace the president each made him a centerpiece of their message to the more than 6,000 caucus-goers, officials, and activists gathered in Des Moines.

In dueling speeches, Hillary Clinton and Bernie Sanders each sought to claim opposite aspects of the Obama mantle.

For Clinton, it was the very Obama legacy — and an eight-year record of "progress," in need of safeguarding. For Sanders, who has suggested the country needs to change direction from Obama's record, it was the underdog spirit and momentum of his 2008 campaign.

Sanders, highlighting how far his campaign had already come in the polls after just six months, predicted his candidacy would be the next to, "prove the pundits wrong again," as Obama's did in 2008.

Pacing the stage, delivering the first speech of the night from the JJ stage, stirring roars from the Hy-Vee Hall, Sanders drew parallels to Obama's campaign, while drawing sharp and aggressive contrasts with Hillary Clinton on one issue after the other: trade, same-sex marriage, and the suggestion that, unlike Clinton, he would govern "based on principle not poll numbers."

In 2008, Sanders told the crowd, there was a candidate pundits called "unelectable" and unknown to the wider electorate. "Remember that guy's name? Oh, it's President Obama."

"Iowa, we're going to prove the pundits wrong again," Sanders said in one of the most spirited speeches of his campaign. "I believe we're going to make history one more time."

"I promise you tonight as your president I will govern based on principle not poll numbers," Sanders said. "I pledge to you that every day I will fight for the public interest not the corporate interests. I will not abandon any segment of American society — whether you're gay or black or Latino or poor or working class — just because it is politically expedient at a given time."

In an interview this week, Sanders dismissed the inherent "tension" in calling for a new direction, while still praising Obama. Sanders told MSNBC's Chris Hayes that, "given the crisis we face right now with the power structure in America," American voters needed a "political revolution." When Hayes asked if the administration shared that view, Sanders replied, "Not really."

Clinton, following a speech by Martin O'Malley, took the stage to sustained applause from the largest contigent of supporters in the hall, lit up in neon blue by hundreds of campaign-issue glow sticks.

Her Jefferson-Jackson speech did not differ much from the one she typically gives at campaign stops. But Clinton had a greater focus on the the need to defend and preserve Obama's record by electing a successor from the party, remiding voters here, "I am running as a proud Democrat." Sanders is seeking the nomination as a registered Independent.

As supporters chanted, "I'm With Her," Clinton was also sure to thank Joe Biden, who earlier this week announced after months of intense speculation that he would not seek the Democratic nomination. "Let's show him how much we appreciate Vice President Joe Biden," Clinton said, noting that Biden was by Obama's side, "every step of the way."

"We need to defend the progress that we've made under President Obama," Clinton said, arguing as she often does that her former opponent doesn't get the credit he deserves for steering the country through a recession.

For Clinton, the strong performance on Saturday would cap off what has so far been the best month of her campaign: After a difficult summer, with flagging poll numbers and negative headlines about the personal email account she used as secretary of state, Clinton delivered a decisive victory in the first Democratic debate, and this week won praise for her marathon 11-hour testimony before the House Select Committee on Benghazi.

Before the JJ dinner, her campaign hosted a rally outside Hy-Vee Hall with Bill Clinton, making his debut as a surrogate for his wife — along with singer Katy Perry, who also attended the dinner, seated at a table near the stage.

Sanders, still polling competitively with Clinton in Iowa and New Hampshire, aimed on Saturday to showcase the excitement around his campaign, as Obama did here in 2007, with thousands in the hall for a speech that immediately out-shined his primary opponents, Clinton and John Edwards.

Joe Trippi, a strategist on the Edwards campaign, remembers standing in Hy-Vee Hall that night eight years ago — head down, eyes fixed on his shoes — with just one thought as he listened to Obama's rousing speech: "That's it."

"You knew that night," Trippi said.