MADISON, Wis. -- Scott Walker announced Monday he is dropping out of the GOP presidential race.
The Wisconsin governor entered the primary in July as a front-runner in Iowa and a darling of both the conservative base and powerful donors after winning battles against public unions in his left-leaning home state. But that promising start was quickly dashed after poor debate performances dried up support from donors.
"Today, I believe that I am being called to lead by helping to clear the field in this race so that a positive, conservative message can rise to the top of the field. With this in mind, I will suspend my campaign immediately," Walker said at a news conference.
He encouraged other trailing Republican candidates to follow his path.
"I encourage other Republican presidential candidates to consider doing the same so that the voters can focus on a limited number of candidates who can offer a positive, conservative alternative to the current front-runner," said Walker, referencing businessman Donald Trump. "This is fundamentally important to the future of our party, and, more important, the future of the country."
The governor called some of his top supporters earlier Monday afternoon informing them of his decision, according to one Walker insider. This person said Walker's recent plummet in the polls was a big factor in his decision-making.
He sounded "upbeat," they said, and his message to supporters was, "I did the best I could."
Walker made "the Pawlenty decision," one strategist said, referring to former Minnesota Gov. Tim Pawlenty's 2011 decision to drop out before piling up considerable debt.
This decision came as no surprise to people working in Madison, one of whom described the last several weeks as "agony."
Moving forward, Walker said the best use of his and the party's time would be to dedicate all resources to the eventual nominee.
Walker's exit comes 10 days after former Texas Gov. Rick Perry became the first Republican to drop out of the 2016 race. It indicates the start of a winnowing process of a field that once numbered 17 candidates -- many of whom have struggled to gain oxygen in a summer in which headlines and polls have been dominated by Trump. With Walker's departure, the field stands at 15 candidates.
The New York Times first reported Walker's plans to drop out. Those intentions were confirmed by a senior campaign official, a GOP strategist close to the campaign, and a senior GOP adviser with knowledge of his plans.
Walker rocketed to the front of the GOP pack in Iowa after a rousing speech at the Iowa Freedom Summit in January -- and subsequently, his campaign pinned its hopes on the first state to vote in the presidential nominating process.
But Walker was hurt by lackluster performances in the first two Republican debates. And his poll numbers suffered: In a CNN/ORC poll released Sunday, Walker failed to garner even one-half of 1 percent nationally among likely GOP primary voters.
A GOP strategist close to the campaign said Walker "is a pragmatist above all else and just didn't see the path to a comeback."
The strategist also said that the Walker campaign left last week's debate feeling alright, but quickly realized the outside reaction was flat at best. This source added that the national polling drop was troubling but it was the collapse in Iowa that hit hardest, as that state was to serve as "our launchpad."
"Hard to see a path for us without Iowa," one source said.
There had always been hope in the Walker campaign that Trump supporters were not active caucus-goers, the source said, but it was hard to fight the popularity of both front-runner Trump and Ben Carson.
Walker was also hurt by reversals on a host of controversial issues -- including birthright citizenship, on which he gave three different answers in the span of seven days. Those reversals were particularly damaging to his outsider image as non-politicians like Trump, Carson and Carly Fiorina climbed the polls.
Walker delayed entering the campaign in part to raise money for his super PAC, which posted a $20 million haul in the first half of 2015.
But once it launched, the campaign appeared to be bedeviled by a lack of hard dollars that it needed to pay staff, travel the country and pay filing fees to state parties. It will not be known how much money the Walker campaign raised -- or how quickly it burned through it -- until October 15, when the federal campaign finance reports are made public.
"The money dried up -- and it dried up right after the Cleveland debate, and we never could get it back," a source close to Walker said of the August 6 debate.
The super PAC will "wind down our existing efforts and return remaining resources to supporters," according to a spokesman for the group.
Aimee Locke, a top Texas fundraiser for Walker, said she got no advance notice from the campaign, but said people in her network began to worry as CNN's new poll results showed Walker with less than 1 percent support nationally.
"We were told that they were going to be some changes made, but we had no idea that this was the change that was going to be made," she said.
Walker's exit is now almost certain to set off a fierce scramble for his big-money backers, led by the Ricketts family that has emerged as one of the GOP's most powerful financial contributors. Todd Ricketts, the campaign's finance chair, was scheduled to host a fundraiser for Walker in New York on Thursday.
Trump complimented Walker on Twitter after the news of his decision broke.
"I got to know @ScottWalker well -- he's a very nice person and has a great future," he said.
South Carolina Sen. Lindsey Graham, also a GOP presidential contender, said Walker made the decision that was "best for him and his family."
"You are down to 15. You got three basketball teams. The bottomline is Scott made a decision best for him and his family," Graham said. "He's a very accomplished governor and it shows you just how hard it is running with this many people. That's what it shows."
AFL-CIO President Richard Trumka had some choice words for Walker -- best known for his anti-union efforts.
"Scott Walker is still a disgrace, just no longer national," Trumka said.