Ames, Iowa – This wasn't the first time Jeff Stavnes has watched Florida Sen. Marco Rubio in action. But this, he said, was by far the best.

The Republican presidential candidate gave a loose, cutting and at times funny stump speech Saturday before a few hundred Iowans who waited in a cramped student center for more than an hour to hear him. And Stavnes, who is torn over whether to caucus for Rubio on Monday, said he’s giving the candidate a second look.

“He’s gotten better over time,” he said.

The Florida senator is at third in most polls of Iowa voters ahead of Monday’s caucus, and he’s been the target of increasing attacks from Texas Sen. Ted Cruz and other contenders. But some recent surveys show he’s inching up, and his crowds are growing larger in the final days before Monday’s caucus.

At Saturday’s rally, Rubio presented himself as the sole candidate who can consolidate mainstream Republican support while also appealing to the conservatives and evangelicals on its flank. He also made an argument to grow the GOP from its conservative core by appealing to more working class voters.

“We’re going to unite this party quickly. We have to grow the conservative movement. We have to,” said Rubio, casting himself as the one candidate Democratic frontrunner Hillary Clinton most fears.

“I grew up paycheck-to-paycheck. I lived paycheck-to-paycheck. And people in my family still live paycheck-to-paycheck.”

His campaign has stocked up for the final, furious charge over the next two days. He's outlined plans to air 30-minute TV specials in every media market across the state, and he's planning at least a half-dozen rallies over the next few days.

The target on Rubio’s back is growing as he rises in the polls. Cruz has shifted most of his negative advertising away from frontrunner Donald Trump and to Rubio in this final stretch, leveling new attacks on his immigration stance.

Rubio, meanwhile, tried to dismiss the negative ads as a type of “kitchen sink” attack from a desperate opponent in the final days of a heated race. His aides fanned out through the crowd, in search of new supporters to commit to caucus for him.

Jeff Stavnes still isn’t sure – he said he’s leaning toward one of the governors running for the nomination – but his wife Janice left the rally convinced.

“Just listen to him talk. Listen to where he came from,” she said. “Cruz seems a little arrogant. Rubio, I just adore. He’s a little young. But Kennedy was young, too.”