Clinton, Iowa (CNN) Hillary Clinton boiled down her closing message to Iowa voters into three words on Saturday: "We can't wait."

But just across this Mississippi River city, to a far larger crowd, Bernie Sanders had a message of his own: "It's time for a political revolution."

The dueling arguments between Clinton and Sanders were on vivid display: Clinton implored her supporters to consider her experience when making their voices heard in the Iowa caucuses on February 1. Sanders urged his admirers to fight the establishment and dream big.

Using the refrain repeatedly, Clinton put her presidential experience in stark terms by telling detail-laden stories about her political life, including one about dealing with a terrorist threat around President Barack Obama's first inauguration from the White House's Situation Room.

"I was able to bring my years of experience to the forefront," Clinton said about having to decide whether to go on with the inauguration despite the threat against Barack Obama, who she described as the nation's "newly elected young dynamic president." "This is one of the biggest parts of the decision as you head toward February 1 that I want you to keep in mind. We're living in a complicated world, to say the least. We know we have a terrorist threat -- and I've laid out a detailed set of recommendations of what to do."

The anecdote, which gripped town hall attendees here, squares with Clinton's closing argument: I am ready for the presidency on Day 1 and you and your family don't have time to wait for someone to learn on the job.

The refrain is a clear knock against Sanders, who drew a far more boisterous crowd to his rally about an hour later. He took note of the proximity of his rival and drew booming applause as he mentioned her by name.

"You can tell when a campaign gets nervous -- like the Clinton campaign -- and I think they're getting a little nervous, what do you think?" Sanders said. "When candidates and campaigns get nervous, they start throwing out a bunch of stuff."

Clinton and her aides have tried to stem Sanders' surge by casting his ideas as too idealistic to be implemented. And even if they are, Clinton argues, it will take too long.

The refrain is a clear knock against Sanders, whose upstart primary challenge has stunned some of Clinton's closest aides.

"For me, it really comes down to this: We can't wait," Clinton said during the town hall. "We can't wait to help Ellen with her exorbitant prices. We can't wait to help the minimum wage workers I meet who are working one, two jobs and still can't figure out how they are going to gather enough money to make any progress. We can't wait to deal with the student debt that so many young Iowans tell me they are struggling under."

Sanders told Iowa voters to disregard Clinton's call for experience, saying it sounded like the same argument she made against Obama.

"It really reminds me what happens here in Iowa eight years ago," Sanders said. "He was being attacked. He did not have the experience that was needed. People of Iowa saw through those attacks then and are going to see through those attacks again."

Race far tighter than expected

The Democratic race is heading into its final week far tighter than either side expected. The enthusiasm on Saturday favored Sanders, who drew a far younger and more energetic crowd that chanted: "Feel the Bern!"

Crowd sizes, particularly in an Iowa caucus campaign, tell only a small part of the story. The question is how many supporters will turn out on February 1 to 1,681 precincts across the state.

Clinton's focus on urgency is a direct rebuttal Sanders and his supporters who view the former secretary of state's pragmatism as a desire to go slow and compromise. The Vermont senator regularly says that "establishment politics" -- a not-so-subtle euphemism for Clinton -- won't be able to solve the nation's problems.

Clinton looked to rebut that point Saturday when she argued that the country's problems are too big to propose wholesale changes and instead pushed incremental victories.

"We can't wait," Clinton said. "We have urgent business to do in America and if you give me the chance, I will work my heart out for you and I will continue to learn from you and make sure that we move forward."

Clinton worked the argument into a host of issues, stressing both the urgency to get them done and her experience.

"My esteemed opponent, Senator Sanders, wants to start all over again," Clinton said on health care, charging Sanders with wanting to roll back the Affordable Care Act to implement his Medicare-for-all, single-payer vision. She added that their disagreement on the issue "is not over the goal."

"We share the same goal," said the former first lady. "Universal health care coverage for every single American."

Sanders directly acknowledged the criticism, saying: "If people want to attack me for this, that's fine. " But he argued that his plan to create universal health care coverage could be achieved by rallying a political movement so the United States could "join the rest of the civilized world."

"Will Iowa be the first state in the union to embark upon a political revolution to lead this country in a very different direction?" Sanders said. "You know what? I think that's exactly what you will be doing."

The urgency argument also helps Clinton with turning out voters.

Sanders and Clinton will be criss-crossing each other for much of the next week. Both Democratic candidates are holding events in Clinton and Davenport, Iowa, on Saturday, and over the next week, the candidates will hit similar towns and media markets in an effort to rally their die-hard supporters and convince those voters on the fence to fall their way.

Clinton's campaign aides have long been concerned with complacency among their supporters, in part because Clinton started the presidential are with sizable leads nationally and in early states. Now that many of those leads have evaporated, Clinton and her aides have implored their voters to stand by her.

"I need you," Clinton has told voters recently on the ropeline. "I need you."