Henniker, New Hampshire (CNN) When Marco Rubio blazed out of Iowa riding high on his surprisingly strong third-place finish, one thing immediately became clear: He was heading into the New Hampshire primary with a target on his back.

The race is still two days away. Donald Trump continues to top the polls here, holding an 11-point lead over Rubio in a recent CNN/WMUR poll. But as the candidates race around the state on the final weekend of campaigning, some 30% of likely GOP primary voters remain undecided. And interviews with voters here suggest that this is a remarkably fluid race.

For weeks now, Trump's rivalry with Ted Cruz has dominated the presidential race, but the spotlight in New Hampshire is on the heated battle in the establishment lane between Rubio, John Kasich, Jeb Bush and Chris Christie. That feud unfolded Saturday night at the final Republican presidential debate before the primary on Tuesday.

Christie relentlessly attacked Rubio as someone who delivers soaring speeches but has never made a consequential decision in his political life and isn't fit to be president.

"Marco, the thing is this," Christie said at the ABC debate at St. Anselm's College in New Hampshire. "When you're president of the United States, when you're a governor of a state, the memorized 30-second speech where you talk about how great America is at the end of it doesn't solve one problem for one person," Christie said.

Jeb Bush added to the Rubio criticism, saying that Americans shouldn't gamble on a candidate who doesn't have executive experience.

"Marco Rubio is a gifted politician and he may have the skills to be president of the United States," Bush said.

Photos: Who's running for president? Photos: Who's running for president? Ted Cruz, Donald Trump, John Kasich, Hillary Clinton and Bernie Sanders, Hide Caption 1 of 6 Photos: Who's running for president?



"So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Businessman Donald Trump announced June 16 at his Trump Tower in New York City that he is seeking the Republican presidential nomination. This ends more than two decades of flirting with the idea of running for the White House."So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Hide Caption 2 of 6 Photos: Who's running for president?



"These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Sen. Ted Cruz of Texas has made a name for himself in the Senate, solidifying his brand as a conservative firebrand willing to take on the GOP's establishment. He announced he was seeking the Republican presidential nomination in a speech on March 23."These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Hide Caption 3 of 6 Photos: Who's running for president? Ohio Gov. John Kasich joined the Republican field July 21 as he formally announced his White House bid.



"I am here to ask you for your prayers, for your support ... because I have decided to run for president of the United States," Kasich told his kickoff rally at the Ohio State University. Hide Caption 4 of 6 Photos: Who's running for president?



"Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hillary Clinton launched her presidential bid on April 12 through a video message on social media. The former first lady, senator and secretary of state is considered the front-runner among possible Democratic candidates."Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hide Caption 5 of 6 Photos: Who's running for president?



"This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Sen. Bernie Sanders , an independent from Vermont who caucuses with Democrats, announced his run in an email to supporters on April 30. He has said the United States needs a "political revolution" of working-class Americans to take back control of the government from billionaires."This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Hide Caption 6 of 6

But Bush then compared Rubio to President Barack Obama, who entered the White House without executive experience.

Better ideological fit

Trump may be capturing the attention of many first-time voters. But the four mainstream candidates have always been a better ideological fit for the state's more moderate GOP voters, as well as the large bloc of independents, who could have an outsized influence on Tuesday's results.

For months, Rubio, Bush, Kasich and Christie have labored in Trump's shadow, struggling to gain a foothold in this famously mercurial state. But Iowa's results have scrambled the 2016 race in unexpected ways. Rubio is clearly rising in the polls, but many voters here say they are still eyeing the other three "establishment" candidates. And that competition means that arrows are slinging in all directions.

It is unclear whether Trump will be able turn out the untraditional voters drawn to his candidacy. Despite his commanding lead nationally, his second-place finish in the Hawkeye state stripped away the veneer of invincibility around his campaign and raised questions about the efficacy of his ground game. On Thursday, he made the rookie mistake of flying home to spend the night in New York before a snowstorm, forcing him to cancel his Friday campaign schedule in New Hampshire.

So far, there is also little evidence of a major bump for Cruz in the Granite State after his win in Iowa. The Texas senator cuts a far more conservative profile than most GOP voters here, and he has clearly been damaged by Trump's attacks on his Canadian birth and his "likability."

Elizabeth Breuder, a 68-year-old Bedford Republican who attended a Rubio event in Manchester this week, said she was torn between Cruz and the Florida Senator, but ultimately settled on Rubio because she doesn't think is as Cruz "likable."

Rubio, Breuder said, "can unify people. He'll attract younger people, Hispanics, and he's very impassioned," she said, adding that Rubio reminds her "a little bit of John F. Kennedy."

"I think Rubio can win hearts. Change minds and win hearts, which Cruz will not do."

In the CNN/WMUR tracking poll , Cruz trailed Trump and Rubio, who notched the support of 17% of voters, and was tied with Kasich at 13%. Bush, the former Florida governor who drew one of his largest crowds Thursday night when he campaigned with his mother in Derry, was not far behind at 9%.

The margin of error is 5.8 percentage points.

Sensing their opening -- particularly because so many New Hampshire voters make up their minds at the last minute -- Bush and Christie both came out swinging ahead of the GOP debate as they try to edge their way to the top-tier and blunt any momentum that the Florida senator might have coming out of Iowa.

Torrent of insults

Christie, the New Jersey governor, unleashed a torrent of insults at Rubio this week -- belittling him as the "boy in the bubble" who hides behind "canned answers," and is not ready to be commander-in-chief.

During a town hall in Henniker on Thursday, Christie mercilessly mocked the fact that one of Rubio's newest surrogates, former Pennsylvania Sen. Rick Santorum, struggled to name a single Rubio accomplishment in the U.S. Senate during an interview with MSNBC.

"They gave Senator Santorum three minutes to name one accomplishment of Senator Rubio. One. Just one. It took him three minutes," Christie said. "He finally came up with: he fought some amendment on Obamacare, at one point."

"Let me tell ya," the New Jersey Governor continued to laughter. "They're saving a place on Mount Rushmore after that one."

Christie, who stands at 4% in the latest CNN/WMUR New Hampshire poll, has campaigned relentlessly here. In the final days, he has sharpened his argument that Rubio is simply too young and too unprepared to be president.

"We have a bunch of talkers in this race... In fact, so far, the talkers seem to be doing ok," Christie told the crowd at New England College. "The kings of talking are any member of the United States Senate. Because that's all they do."

"You have a choice now," Christie said. "The choice now that they have set up in this race is about talkers and doers."

Bush, who has had his former protégé in his sights for months, doubled down on that message in his own ad Friday by using clips from the Santorum interview and touting his own record in Florida.

Asked in an MSNBC interview Friday what Rubio had accomplished in the Senate, Bush replied with a shrug: "Nothing."

"Marco is a talented politician," Bush continued. "He got elected when he was 26 years old. People love him, and I do too, he's a great guy. But he's not a leader."

On top of that scathing criticism, the super PAC supporting Bush, Right to Rise, has spent millions of dollars on ads pummeling Rubio as a political opportunist and a lightweight who missed too many votes in the Senate.

"Two gifted freshman senators that can deliver a great speech, very talented, don't get me wrong -- one of them is a close friend that I admire," Bush said Thursday night in Derry, referring to Rubio and Cruz. "But what in their background would suggest that they could make a tough decision, that they run to the fire to put it out, that they've figured out a way to solve problems?"

Reject 'angry voices'

In his closing pitch, Bush also urged voters to reject the "angry voices," "the loud voices," and "the dividers."

"We don't need the big dog on the stage, barking out stuff, insulting people," Bush said, referring to Trump. "We need someone that has a proven record. That has a servant's heart."

He urged voters to prove the pundits wrong, as they have many times: "You live in New Hampshire, you can change the course of any campaign any time you want."

A Super PAC allied with Rubio, Conservative Solutions PAC, returned fire mocking the lavish spending by Bush and his allies and faulting him for attacking other Republicans. "He spent millions praising himself, and his campaign tanked," the campaign narrator said.

Ohio Gov. John Kasich is testing an entirely different approach -- doggedly adhering to a positive campaign message. His super PAC released an ad mocking the mud-slinging among the other candidates.

"At a time when we are just deluged with negative ads and everything, we are peeking through with a positive message," Kasich told reporters in Pelham.

Asked whether that approach would be enough to give him a win on Tuesday, Kasich hedged: "We're going to see."