Republican candidates confront Trump's enduring popularity in Iowa with 100 days to go until caucuses

On Saturday - 100 days before Iowa Republicans head to their caucasues - Iowa will once again become the focal point of the GOP presidential race as the ambitions of much of the field collide in the Hawkeye State.

It is likely to remain the center of attention for much of the foreseeable future.

Former President Donald Trump's enduring popularity in Iowa and across the early Republican presidential nominating map has forced much of the field to aggressively turn their attention to the state in hopes of stopping his march toward the nomination. Florida Gov. Ron DeSantis in particular has approached the state as a must-win, but others increasingly view it as a last stand to demonstrate that a viable alternative to Trump can emerge before it's too late.

Candidates' planned scripts were scrambled Saturday as Israel's Prime Minister Benjamin Netanyahu declared his country "at war" in the wake of a surprise attack by Palestinian militants in Gaza, who fired a deadly barrage of rockets and sent gunmen into Israeli territory.

DeSantis said Saturday that the US stands with Israel. "They have a responsibility to defend themselves with overwhelming force," he said at a meet and greet at a coffee shop in Ankeny, Iowa, adding that President Joe Biden needs to provide "moral clarity."

Meanwhile, Trump condemned the rocket attacks as an "act of savagery," at a campaign event in Waterloo, Iowa, and deemed the Biden administration as responsible, attempting to connect the attacks to perceptions of Biden's leadership abroad.

Seasoned Iowa operatives and observers say the stakes for the caucuses - which do not traditionally serve as a kingmaker - have rarely felt so acute.

"With Trump having such a gigantic lead going into this home stretch, you're going to know at the end of this caucus if someone can legitimately challenge him or if it's all over," said Jeff Angelo, who broadcasts a conservative radio show in Iowa that presidential candidates regularly appear on. "I really get the sense that the candidates understand it's Iowa or nothing. If you're not close here, there's no strategy to beat Donald Trump."

DeSantis' campaign is not hiding its urgency. It recently moved one-third of its Tallahassee campaign staff to Des Moines and the candidate availed himself to Iowa media most of last week even as he campaigned and raised money elsewhere. On Saturday, he begins a three-day bus tour as he closes in a promise to touch all 99 Iowa counties. He started the day at 58.

A super PAC supporting DeSantis, Never Back Down, has so far spent $9.8 million boosting DeSantis on Iowa's airwaves, more money than any other political committee or campaign, according to data provided by AdImpact. The next closest, SFA Fund. Inc, a super PAC allied with former South Carolina Gov. Nikki Haley, has spent $6.7 million.

"The only thing that truly matters is Iowa," said Pete Snyder, a former gubernatorial candidate in Virginia now raising money for DeSantis. "If you don't win that, no one is going anywhere."

Trump, too, must sense the race in Iowa escalating. After avoiding the campaign trail for much of the summer, Trump has reengaged with the early nominating states, especially Iowa. Trump held a rally in Ottumwa last weekend and he has campaign stops in Waterloo and Cedar Rapids on Saturday. Seven stops in Iowa are planned for October as part of a strategic push to maintain momentum heading into the January 15 caucuses, especially as his rivals hit the ground relentlessly to court voters in the first-in-the-nation nominating state, his advisers told CNN.

For many Republicans, Trump remains the only candidate they will consider.

"I really haven't been involved with any of the other candidates," 29-year-old Zackary Musgrove told CNN at the Ottumwa rally. "I'm all Trump all the way."

However, not all of the recent rally's attendees have made up their mind about who they will vote for. Pat Inmund, 64, told CNN she is looking at all the candidates but is currently planning to caucus for Haley.

"I just like her personality, and she made a comment about how there are so many old people in the Congress, and it's like a nursing home," Inmund said. "And I thought, 'Oh, I like that, you know, we need to have some age limits.'"

Haley is also headed to Iowa this weekend for three campaign stops, including town hall meetings with voters in Sioux City, Ida Grove and Boone. They are the latest in a series of regular visits she's been making throughout the year in all corners of the state.

Haley also intends to intensify her organizational efforts in Iowa, a Republican close to the campaign told CNN, with an announcement set for Monday as she concludes her weekend visit to the state. She is approaching 50 appearances in the state, her campaign said.

More than many of her rivals, Haley has followed a three-state strategy, focusing in equal measure on Iowa, New Hampshire and South Carolina, the first three states on the GOP nominating calendar. She's been working to win over Republicans who are eager to move on from Trump, but have yet to be persuaded by DeSantis or other challengers.

"She's smart, she's tough and she's passionate," said Jane Barth, a Republican voter from West Des Moines who came to see Haley at a recent stop in Iowa, after her performance in the first Republican primary debate caught Barth's attention. "I think she would be fantastic."

Haley is targeting business-minded Republicans, along with women, as she works to build a coalition of support in Iowa. While evangelicals hold considerable sway in the Iowa caucuses, that bloc is expected to be divided among many challengers, which aides say offers her an opening for Republicans looking for the party to take a new direction.

"I think she sees the big picture, from the border to China to Russia," said Katie Clark, a Republican from West Des Moines who puts Haley near the top of her list of choices. "We have to have somebody strong, which I think she is. I'm very pleased with her."

Others have put Iowa at the center of their strategies, too. Also on Saturday, former Vice President Mike Pence and former Arkansas Gov. Asa Hutchinson will try to keep their White House aspirations alive by visiting the state.

South Carolina Sen. Tim Scott has made a push in Iowa as well, appealing to the state's evangelical voters with a faith-focused campaign that has leaned into the anti-abortion fight. His campaign has already spent $6 million on Iowa advertisements and a super PAC supporting Scott has reserved $14.5 million in airtime for the fall - more than twice as much as the pro-DeSantis Never Back Down.

Candidates insist the race is far from settled, noting that Iowa often breaks late.

At this stage of the 2016 nominating fight, neurosurgeon Ben Carson was leading in Iowa and Ted Cruz was polling in the single digits there. Cruz ultimately finished first while Carson fell to fourth. Many of the architects behind Cruz's victory are now trying to engineer a similar late surge for DeSantis in Iowa.

DeSantis' team insists that his strategy - appearing all over the state, running to the right of Trump on abortion and immigration, enlisting local support and knocking on tens of thousands of doors - will prove victorious in a state that has consistently rewarded organized campaigns, lots of face time and deeply conservative candidates.

"The only number that's gone up in Iowa this summer is the Never Trump consideration metric - voters who have self ID'ed as they won't vote for Trump," said Ryan Tyson, a senior adviser to DeSantis' campaign.

The expectation by DeSantis is that a near victory or outright win in Iowa will clear the field and reset the race as a two-person fight with Trump, which is why he is prioritizing Iowa over other early battlegrounds.

Angelo said DeSantis' strategy for now amounted to "hopeful rhetoric," though he added, "But it is the way you have to do it."

None of the 2016 contenders carried a lead in Iowa like the one Trump has sustained since summer. Polls continue to show Trump 30 points ahead of the next closest contender, DeSantis, and approaching support from half of likely Republican caucus goers.

Trump's advisers said they have learned from mistakes his 2016 campaign team, where they had no caucus plan, and remain confident they are positioned to win the state in January.

"Trump is a vastly different candidate now than he was in 2016. He's got a huge reservoir of goodwill with conservative voters," Trump senior adviser Chris LaCivita said. "He's not just a politician who's a businessman saying he's going to do this. He's a former president saying, 'Look what I did.' And he has literally an operation that can backup everything that he says it does."

DeSantis lately has taken aim at that record and has stepped-up his attacks on Trump.

As winter nears with Trump's advantage intact, donors looking to move on from Trump have intensified calls for the field to shrink and clear a path for an alternative to emerge.

Doug Gross, a former chief of staff to Iowa Gov. Terry Branstad, said the state's labor-intensive caucus system - where Republicans gather in churches, schools and community centers, often on a cold winter night and debate for hours who to support - leaves an opportunity for someone like DeSantis or Haley to emerge.

"The problem is right now they need to get some people out of the race," Gross said.

But it's not clear which candidate would benefit most in Iowa from a winnowing of the field. A recent Fox Business survey of Republican caucus goers found DeSantis, Scott, Haley and entrepreneur Vivek Ramaswamy received about equal consideration for second-best candidate. One in 10 surveyed was still unsure who their backup choice would be and 7% chose Trump, suggesting that a consolidated field won't necessarily doom the former president.

Kyle Clare, a University of Iowa student who is an officer with College Republicans there, said he would caucus for DeSantis today but is open to anyone who can challenge Trump.

"We need a different nominee than Trump," Clare said. "So you know, at the end of day, if (DeSantis) falls below second place, someone else is there that I think would be able to defeat him in the state of Iowa, I would caucus for them instead."

CNN's Kit Maher, David Wright, Veronica Stracqualursi and Aaron Pellish contributed to this story.