It’s Official: Scott Walker Has Dropped Out of the 2016 Presidential Race

The roster of Republican Presidential candidates got a little less crowded on Monday, with Wisconsin Governor Scott Walker announcing at a press conference that he is officially suspending his campaign for president.

"Today, I believe that I am being called to lead by helping to clear the race so that a positive conservative message can rise to the top of the field. With that in mind, I will suspend my campaign immediately," said Walker. "I encourage other Republican candidates to consider doing the same."

Walker's announcement came hours after a new CNN poll showed that he had the support of less than 1 percent of likely Republicans voters nationwide. It's a precipitous decline in popularity for Walker, who in July was polling at 21 percent nationally and was in first place in the key primary state of Iowa.

In the days leading up to Monday's announcement, Walker's campaign refocused all of its efforts in the key battleground states of South Carolina and Iowa. These efforts did little to stop the campaign's rapid tailspin, although his announcement on Monday came as a surprise to many.

"I'm completely shocked," said Frank Luntz, a Republican political consultant and polling expert. "I saw Walker on Thursday and he gave no indication [of dropping out]."

Walker is the first candidate to quit the race after the second Republican debate last week, where his performance was widely seen as underwhelming. Walker struggled to distinguish himself on the crowded stage and failed to clarify his position on issues such as birthright citizenship and immigration.

Walker urged Republicans to "get back to the basics of the party," and said that "voters want to be for something instead of against someone."

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After Walker's first debate performance, in which he touted his record on union busting, AFL-CIO president Richard Trumka released a statement that said Walker was a "national disgrace." Today, Trumka stuck by his statement that Walker was still a disgrace, "just no longer national."

— Richard L. Trumka (@RichardTrumka)September 21, 2015

Luntz said that in addition to the low polling numbers, which makes it difficult to raise money from donors, Walker's visible struggle to get his message out contributed to his sinking campaign.

"Voters have to know where you stand and he started to lose his definition," said Luntz. "He was not as disciplined." Walker's campaign was also one of the most expensive in the race, Luntz said, suggesting that high staff costs that could have contributed to the decision to pull out.

Four other Republican candidates — former Virginia Governor Jim Gilmore, South Carolina Senator Lindsey Graham, Louisiana Governor Bobby Jindal, and former New York Governor George Pataki — received the same dismal poll numbers as Walker on Monday. But Walker was the only member of this set that was an early favorite and had participated in the "varsity" debate with the 10 other higher-polling candidates.

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Walker gained national attention for his record of union busting, controversial budget cuts, and surviving a recall election, the first for an incumbent in a gubernatorial race, in his home state of Wisconsin. He was one of the GOP's so-called establishment candidates, who have actually held a political office and are dramatically losing favorability to outsider candidates Donald Trump, Carly Fiorina, and Ben Carson. But Walker's dropping out might make it easier for the other middle-of-the-road candidates, who now have one less competitor to worry about, Luntz said.

Walker's rapid rise and dramatic fall is a familiar pattern for candidates who start off with an early lead. "Normally when you start off as a favorite and then you lose it," said Luntz, "you just don't get it back."

Follow Olivia Becker on Twitter: @obecker928