Council Bluffs, Iowa (CNN) There is no sense of worry in Hillary Clinton or her campaign aides a day before Iowans decide who to caucus for on Monday night.

Polls show Vermont Sen. Bernie Sanders tightening the Democratic presidential primary race, but the former secretary of state and her husband -- former President Bill Clinton -- appear to be at peace with how her campaign has been run and her standing 24 hours before the caucuses.

While most Clinton aides didn't expect the race would be this close, the same aides say they feel like a win is in sight.

"We've had an amazing grassroots organizing effort," Clinton told CNN on Saturday. "I'm so proud of all the people who have put it together and the, literally, tens of thousands of volunteers that they've enlisted."

Mike Gronstal, the Iowa Senate Majority Leader and top elected Democrat official in the state, also endorsed Clinton on Sunday at a rally in his hometown of Council Bluffs.

"They all have all the right issues on their side, but there is one of them through thick and thin who has been able to actually get things accomplished. She is the most prepared presidential candidate in the history of the world," Gronstal said of Clinton.

Bill Clinton -- who was critical of his wife's operation in the wake of her failed 2008 bid -- has expressed confidence this time around, applauding Clinton's Iowa organizers and urging them to do as much as they can in the next 36 hours.

"We just have to keep the pedal to the metal until the last day," Clinton said after Saturday's event. "We need to get her as front as many people as possible."

One reason for the confidence: A deep belief in their organizing program and the modeling they are using to find their pathway to victory.

The Clinton campaign has 4,200 precinct captains and other precinct leaders prepared for Monday night and has seen their volunteer numbers swell in the closing days. On Friday, according to aides, 2,000 volunteer shifts were completed across Iowa, a number that was nearly doubled on Saturday.

And by Sunday, according to aides, campaign volunteers will have knocked on 125,000 doors this weekend alone.

"If you will go caucus for me Monday night, if you will go stand up for me here, if you will be there for me, I promise you this, I will stand for you," Clinton told voters on Saturday night in Cedar Rapids. "I will fight for you through this campaign and in the White House."

Polls in Iowa are tight, especially when one considers that lead Clinton had months ago. A Saturday poll by the Des Moines Register and Bloomberg Politics found Clinton with a 3 point lead over Sanders, well within the survey's margin or error.

But Clinton has not responded by increasing her attacks on Sanders -- Quite the opposite.

Clinton unloaded on Sanders earlier this month at an event in Indianola, arguing that she cares about "making a real difference in your life" and not "ideas that sound good on paper but will never make it in the real world."

What amounts to a Clinton attack now, in the closing days of Iowa?

"I know that there are lot of young people who are very attracted by the senator's proposal for free college," Clinton said Saturday. "Here is the difference. I want everybody who can't afford it to be able to have tuition with out borrowing anything. I do not believe giving free college to Donald Trump's young child is in the best interest of all hard working Americans who need help."

By comparison, Sanders has not muted his attacks, a fact Clinton aides feel show the senator knows he needs to make up ground on the former first lady.

"I would ask you, check the record and find out where my opponent was on all of these issues," Sanders implored his supporters on Friday. "It's great to be against the war after you vote for the war. It's great to be for gay rights after you insult the entire gay community by supporting (the Defense of Marriage Act). Kicking and screaming on (Trans Pacific Partnership), but where were you on all the other trade agreements? It was great to be against the Keystone pipeline after supporting the Keystone pipeline."

Sanders, in the days before voters caucus, has enjoyed an surge of excitement, too. He rallied with more than 3,000 people in Iowa City on Saturday night, a show of strength hours before the caucuses. And his campaign aides, due to growth in the polls, have been claiming they have momentum behind them.

Their key to victory? Turnout.

"From now until Monday night we will be working as hard as possible to knock on as many doors and call as many Bernie supporters as possible," Pete D'Alessandro, Sanders' top Iowa strategist said on Saturday.