CLINTON, Iowa - Donald Trump and Ted Cruz on Saturday continued to jockey for first place in Monday's caucuses, while the other Republicans running for president swarmed nearly every corner of Iowa in an effort to exceed expectations before the campaign heads to New Hampshire.

So-called establishment candidates such as New Jersey's Gov. Christie and Sen. Marco Rubio of Florida suggested that while Trump, a celebrity TV star and businessman, had indeed entertained the electorate, Monday marked a new, more serious stage of the campaign.

Christie on Saturday shared a story of two parents who had told him that their son was deploying for Iraq in a few months. He asked a couple of hundred people at a town-hall-style meeting to "think of that mother and father" when they caucus Monday night.

"I want you to picture them as if they're right next to you, and I want you to be able to look them in the eye and say who you're voting for and say, 'I think this person is the best person to be your son's commander in chief,' " Christie said. "For some people, I think that might change your vote."

Rubio, who is polling third in Iowa, is making a similar case to voters to reject Trump.

"We are not going to win if this campaign becomes a sideshow," he said at a rally in West Des Moines on Wednesday.

He suggested his humble upbringing - the son of Cuban immigrants, his father a bartender - would help him connect with aggrieved voters struggling to make ends meet.

"The Democrats cannot lecture me about living paycheck to paycheck, because I grew up paycheck to paycheck," he said. "They can't lecture me about student loans, because I had a student loan."

Cruz campaigned as a "consistent conservative" who stands up to the "Washington cartel." He has offered a litmus test by which he says voters can judge the candidates' ideological purity and, thus, their fitness for the presidency. And he has aggressively gone after Trump, saying the New York businessman would "expand Obamacare."

Trump on Saturday depicted Cruz as a risky bet, repeating his warning that the senator might not be eligible for the presidency because he was born in Canada.

Otherwise, Trump mostly ignored the other candidates, instead reprising his main campaign theme: The country doesn't win anymore.

"We're going to be respected again, folks," Trump told a few hundred people at a middle-school gym here, 200 miles east of Des Moines. "And we're going to make great deals."

"We are going to build a wall. And who's going to pay for the wall?" he asked the crowd. "Mexico!" it responded.

Christie, who polls in single digits in Iowa, took aim at that idea and Trump's broader immigration proposals.

"Here's my problem with that idea, and with a lot of the ideas that have been expressed in that campaign," Christie said. "No one ever asks the follow-up question: How? 'I'm going to deport 11 million people in two years.' How?"

But he reserved his harshest criticism for Rubio and Cruz, reminding his audience in Cedar Rapids of a moment in Thursday's debate when Fox News showed clips of Rubio and Cruz staking out positions on immigration that they later denounced. During the debate, the senators suggested they hadn't changed their positions.

"It's OK to change your mind," Christie said, adding he had done so, too, on issues such as abortion rights. "Just tell us."

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