Clinton once called the TPP the “gold standard” of trade deals as she helped negotiate it as President Obama’s secretary of state.

On the Keystone XL pipeline, which Clinton seemed to favor as secretary of state but recently opposed, Sanders said he was there first too.

“If you agree with me about the urgent need to address the issue of climate change, then you would know immediately what to do about the Keystone pipeline. Honestly, it wasn’t that complicated,” he said. “To me, that was a no-brainer and that is why I have opposed the Keystone Pipeline from the beginning.”

On the Iraq War vote, where Clinton now says her “yes” vote was a mistake, Sanders said he was there first as well. “Let me tell you that I listened to what Bush had to say, to what Cheney had to say, to what Rumsfeld had to say. I didn’t believe them and I voted no,” he said.

And on the Defense of Marriage Act, the 1996 law signed by Bill Clinton that banned the federal government from recognizing gay marriages — which Hillary Clinton now opposes — Sanders said he was there first once again.

“Today, some are trying to rewrite history by saying they voted for one anti-gay law to stop something worse. Let us be clear. That’s just not true,” he said. “There was a small minority opposed to discriminating against our gay brothers and sisters. Not everybody held that position in 1996.”

Clinton told MSNBC’s Rachel Maddow Friday that her husband supported DOMA as a “defensive action,” since something worse would have been passed in its stead.

On every issue, Sanders said he faced a “fork in the road.”

“I am proud to tell you when I came to that fork in the road I took the right road even though it was not the popular road at the time,” he said.

And one of his biggest applause lines, ostensibly on campaign finance, was also a veiled shot at Clinton. “I am the only Democratic candidate for president who does not have a Super PAC and we are going to prove them wrong,” he said. Clinton has two super PACs.

Sanders sought to position himself as the rightful heir to Obama, who stunned observers at this very event in 2007 by delivering an inspiring speech that drew clear contrasts with Clinton.

“Eight years ago the experts talked about how another Democratic candidate for president, Barack Obama, couldn’t win. How he was unelectable. Well Iowa, I think we’re going to prove the pundits wrong again. I believe we will make history,” he said.

Clinton, meanwhile, drew her own contrast with Sanders on guns, a major weakness for the insurgent, reciting a line she used since last week’s Democratic presidential debate in Las Vegas. ”I’ve been told to stop shouting” about guns, she said. “Sometimes when a woman speaks out some thinks it’s shouting.”

The candidates spoke in the round, surrounded by their supporters, who were sectioned off from each other. Each bloc competed for which could have the loudest cheers, cleverest chants, and biggest shows of strength.

Sanders supporters supplemented their official gear with home-made signs and T-shirts, and chants often arose organically. Clinton’s supporters, meanwhile, appeared as a blue army dressed in campaign T-shirts and armed with double-fisted glowing foam wands.

Earlier in the day, the campaigns held pep rallies across the Des Moines river from each other. Sanders’ featured an eclectic mix of musicians, including black gospel singers.

Clinton’s campaign flew in pop star Katy Perry, who delighted 4,000 fans and wore a dress decked out with red and blue "H" logos for the campaign. Later, she sat at a table with Clinton volunteers near the stage.

Clinton had another special guest up her sleeve too — her husband. Bill Clinton made his debut on the campaign trail for his wife’s second presidential bid, joking that it was time for a first gentleman.

"I want you to support Hillary for me too because I want to break a ceiling. I am tired of the stranglehold that women have had on the job of presidential spouse and I want you to help me deal with that,” he said.