(AP) -- Bernie Sanders implored Iowa supporters Saturday to get on their feet in two days and turn their monthslong infatuation with his upstart campaign into actual votes -- a call to action echoed by Democratic and Republican hopefuls in a frenzied weekend prelude to the first presidential contest of the 2016 race.

On the Republican side, Ted Cruz directed much of his last-gasp advertising against Marco Rubio, as if hearing the Florida senator's footsteps creeping up on him. Cruz chugged across the state on a mission to visit all 99 counties before Monday's caucuses.

Considered to be vying with front-runner Donald Trump, Cruz denounced the next in line, according to polls, with ads sharply challenging Rubio's conservative credentials. One ad said darkly of Rubio: "Tax hikes. Amnesty. The Republican Obama."

"A deceitful campaign," Rubio said in response to Cruz. "Kitchen sink attacks," he said. "That's what they throw at you."

Trump, the showman of the Republican race and its front-runner, made a dramatic entrance to a Dubuque rally as his jet flew low over a hangar half-filled by the waiting crowd and music played from the movie "Air Force One." There was more drama inside, as a small group of protesters interrupted him and Trump joined the crowd in chanting "USA" to drown out the discord.

He asked security to "get them out" but "don't hurt them."

Iowa offers only a small contingent of the delegates who will determine the nominees, but the game of expectations counts for far more than the electoral math in the state. Campaigns worked aggressively to set those expectations in their favor (meaning, lower them) for Iowa, next-up New Hampshire and beyond.

Asked whether Rubio could win or come second, his senior strategist Todd Harris laughingly responded with an obscenity and said the goal in Iowa is third, behind the flamboyant Trump and the highly organized Cruz.

"There's no question we are feeling some wind at our back," he told The Associated Press. But, he added, "It's very hard to compete with the greatest show on earth and the greatest ground game in Iowa history. So we feel very confident that what we need to do here is finish a strong third. I don't care what any of the polls say, Ted Cruz is going to win this caucus."

With that, he tried to set expectations so that if Rubio finishes better than third, it can be proclaimed a great performance and if Cruz doesn't win, it will be seen as a great failure.

At a Manchester rally, Sanders spoke for many when he called the Democratic contest against Hillary Clinton a likely tossup, to be won and lost according to how many Iowans invest the time and energy to make it to caucus sites.

"It's virtually tied," Sanders said, a reasonable summation of polls. "We will win the caucus on Monday night if there is a large voter turnout. We will lose the caucus on Monday night if there is a low voter turnout."

The Vermont senator and Democratic socialist said "the eyes of America, in fact much of the world" would be on Iowa, and the state could be a model for the nation and the future of American democracy. But people need to come out in droves to make that statement.

"When ordinary people, working people, middle class people, seniors, young people become involved in the political process, we can transform this country and we can win here in Iowa," Sanders said.

Clinton has worked assiduously to avoid a repeat of 2008, when then-Illinois Sen. Barack Obama scored a surprise win in Iowa, she dropped to third and her days as the prohibitive favorite for the nomination faded. She faced the prospect of escalating political heat from revelations Friday that the private email server she used when she was Obama's first secretary of state contained top-secret messages that should have remained within proper, secured channels.

That heat was coming from Republicans; Sanders earlier declared the email flap a nonissue in his mind.

But at his Manchester rally, Ruth Lewin, a retired grocery store clerk and child care provider, said the latest news about Clinton's emails reinforced why she will be caucusing for Sanders on Monday.

"It's a matter of honesty, integrity along with other issues I have about her," Lewin said. "When you get $600,000 for a speaking engagement, I mean that's more than I've made in my entire lifetime."

And Sanders? "I believe he's like we are," she said.

Clinton campaigned at Iowa State University in Ames with gun-control advocates Gabby Giffords and husband Mark Kelly, drawing an implicit contrast between her push for stricter laws with Sanders' mixed record on guns

"How can we continue to ignore the toll that this is taking on our children and our country?" Clinton asked. "When you go to caucus Monday night please think of this."

The Clinton and Sanders campaigns reached agreement to hold a debate in New Hampshire this coming week and three more in the spring, supplementing a light debate schedule that has favored weekend slots when fewer people watch TV. The tentative New Hampshire event is to be held Thursday, giving voters a chance to see the field debate before the state's primary Feb. 9.

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Bauer reported from Ames, Iowa. Associated Press writers Steve Peoples, Lisa Lerer and Tom Beaumont in Iowa and Julie Bykowicz in Washington contributed to this report.