DES MOINES — Hillary Clinton and Bernie Sanders drew sharp contrasts with each other at a CNN Democratic town hall in Des Moines, Iowa, on Monday — exactly one week before voters there attend the first in the nation caucuses.

Clinton said she was “really touched” by President Barack Obama’s praise for her in a recent interview as she tried to portray herself as the most effective potential guardian of his legacy. She pushed back against questions that asked why some younger voters are less enthusiastic about her candidacy than that of Sanders. And pressed on whether she was late in addressing income inequality, she said she has spent decades combating inequality of all kinds.

“Don’t get discouraged,” Clinton said. “It’s hard. If it were easy, hey, there wouldn’t be any contest. But it’s not easy. There are very different visions, different values, different forces at work, and you have to have somebody who is a proven fighter — somebody who has taken them on and won, and kept going, and will do that as president.”

Passionate final argument

Sanders, meanwhile, hit Clinton hard over Iraq, trade, the Keystone Pipeline and Wall Street regulation as he drove home a passionate final argument to Iowa voters. He sought to portray himself as the true personification of change in the Democratic race for the White House. He argued that though Clinton has wide experience, she was wrong on key issues.

“We need a political revolution,” he said. “We are touching a nerve with the American people who understand that establishment politics is just not good enough.”

Sanders dismissed Clinton’s political record, seeking to prove he was closer to the Democratic Party base and just as prepared to be president as Clinton.

“I voted against the war in Iraq … Hillary Clinton voted for the war in Iraq,” Sanders said. “I led the effort against Wall Street deregulation. See where Hillary Clinton was on this issue.”

“On day one, I said the Keystone Pipeline was a dumb idea. Why did it take Hillary Clinton a long time before she came into opposition to the Keystone Pipeline? I didn’t have to think hard about opposing the Trans Pacific Partnership. It took Hillary Clinton a long time to come on board that.”

He also warned unapologetically that taxes would rise if he is elected President, especially to pay for his Medicare-for-all health care plan.

“We will raise taxes. Yes we will,” Sanders said.

Sanders argued, however, that the taxes are worth it, given what American families will save in premiums. And, living up to his image as a self-declared Democratic socialist, he warned corporations and the richest Americans that they would pay more.

“Yes, you are going to start paying for your fair share of taxes,” Sanders said. “I demand that Wall Street start paying its fair share of taxes.”

Sense of humor

For a candidate who has been caricatured as overly serious, Sanders’ sense of humor came through at the town hall. He laughed with ease during exchanges with moderator Chris Cuomo and boasted of his athletic prowess as an elementary school basketball player.

Clinton, meanwhile, hugged Obama close, and said she was deeply affected by an interview that Obama conducted with Politico in which he appeared, without making a formal endorsement, to argue Clinton was uniquely qualified for the presidency.

“I was really touched and gratified when I saw that,” Clinton said, relating how her relationship with her former 2008 Democratic primary rival developed into a close friendship when she served as his first-term secretary of state.

The Democratic presidential candidates appeared one after the other for a half hour each at the town hall meeting at Drake University. The forum will showcase the contrast emerging between Clinton, the national front-runner and Obama’s first secretary of state, and Sanders, who is mounting a stronger than expected challenge.

Long shot candidate Martin O’Malley also appeared on stage and argued that he represented a generational change in politics that neither Sanders nor Clinton could match.

Latest polling

Latest polling shows Clinton and Sanders locked in a tight contest in Iowa. In the most recent CNN Poll of Polls, Sanders edges Clinton 46% to 44% in Iowa, with O’Malley at 4%.

And in a new CNN/ORC national poll published on Monday, Clinton led Sanders 52% to 38% with former Maryland Gov. O’Malley way back on 2%. Though the survey showed a significant cushion for Clinton, her advantage was smaller than at any time since September. The poll showed women, non-whites, self-identified Democrats, and those over age 50 breaking sharply for Clinton. Men, white voters, independents who lean Democratic and younger voters are more likely to support Sanders.

The Iowa contest is particularly important to Clinton, who lost the state in 2008, setting in motion Obama’s path to the White House. A victory for Sanders could reshape the entire Democratic race while a Clinton win could quell jitters in her camp and help put her on the path to the nomination.

Clinton, however, insisted she wasn’t worried.

“I’m proud of the campaign we’ve run and what we’ve put out there before the American people,” she said. “It’s a tough campaign and it should be because it’s the toughest job in the world.”