Scott Walker speaks to the media in the spin room after last week's Republican presidential debate at the Ronald Reagan Presidential Library in Simi Valley, California.Bloomberg AFP/Getty

Scott Walker’s sudden suspension of his presidential race is one of the biggest surprises in presidential politics this year. The Wisconsin governor, who looked like a serious contender to win the nomination, saw his standing diminish over the summer as flashier, more-outspoken conservative challengers stole the limelight. Three months ago, he was polling in first place in Iowa and in some national polls. In the CNN/ORC national poll of Republicans released Monday, Walker didn’t even register at 1 percent among Republican voters.

Walker’s withdrawal offers some clear lessons for the 14 remaining candidates—about the importance of raising hard money, having a clear message designed for the long haul, understanding the toxicity of being involved in politics, and the importance of foreign policy in today’s Republican Party.

Here are five of the most important takeaways from Walker’s withdrawal:

1. Hard money (and spending discipline) matters. It’s ironic that, in the age of the super PAC, when it’s easier than ever to raise outside money, two accomplished big-name governors dropped out in the summer in part because they couldn’t raise enough hard money to sustain their operations. Walker, who entered the race July 13, had the support of a well-funded 527 (which raised $20 million at the end of June) and the excitement of many of the wealthiest donors in the party. Now, before he even has a chance to file his first fundraising report, he’s out of the race because he couldn’t get enough donors to commit to his campaign. “No amount of super PAC $ can suffice for hard dollars,” a Walker adviser told National Journal in an email.

Super PACs can’t pay for travel and campaign staff. And if leading candidates race to hire top staff early and can’t bring enough money into the race, they’re in serious trouble. Outside of Jeb Bush, Walker had one of the largest, most expensive staffs of any candidate. When donors started panicking about the lack of progress with the campaign this summer, it created a vicious cycle where it was hard for him to raise enough money to pay the bills and travel across the country.

When assessing the upcoming third-quarter reports, look as closely at the hard dollar totals as the impressive super PAC funds. It’s worth noting that Sens. Ted Cruz and Marco Rubio led the hard-money pack in the second quarter; both are well-positioned to go further along even if they suffer setbacks along the way.

2. Long-term strategy, not short-term tactics, will win the GOP nomination. From the beginning of the race, Walker viewed himself as his own best strategist—a glaring red flag that foreshadowed his problems. In reality, Walker understood tactics, but didn’t have anyone on his campaign payroll that was focused on long-term strategy.

Walker began the race by focusing on his credentials as a fiscal conservative, reminding voters about his fight with Big Labor in Wisconsin and his cuts to government spending. But as Iowa looked like a tempting target, his campaign got distracted by social issues. After the Supreme Court ruled in favor of legalizing gay marriage, Walker went further than all the establishment-friendly candidates by backing a constitutional amendment overturning the decision. Not only did Walker turn off Chamber of Commerce-oriented Republicans with his socially conservative turn, but he found that the pandering didn’t help him much either, since he was competing against more authentic challengers on that front—including Ben Carson, Mike Huckabee, and Cruz. And by telegraphing so early that he was going all-in for Iowa, he boxed himself into a point where it became Iowa-or-bust for his campaign—just at the same time as he was being overtaken by other candidates.

3. Know your foreign policy. At a time when Republican voters are as concerned about the threat of terrorism as the state of the economy, Walker’s inexperience dealing with the subject became a liability. He drew criticism from conservatives at this year’s CPAC conference when he said his success taking on labor unions in Wisconsin prepared him for dealing with the growing threat of the Islamic State. He doubled down on that point for a while until realizing it was a liability—and later crammed in foreign policy study sessions. Walker’s early trip to London, and avoiding public answers to serious questions, only raised questions about his readiness to be commander-in-chief. And his inclination to use clever prepared talking points to discuss foreign policy—“if you find mush, you push” was a favorite line of his—couldn’t match the more serious answers on the subject from candidates such as Rubio, Bush, and even Carly Fiorina.

4. In today’s GOP, it’s better to be a tough-talking outsider than an accomplished conservative insider. Walker’s campaign theme pointed to his record as a governor who fights the liberal establishment—and wins. But on the campaign trail, his mild-mannered personality didn’t match the mood of an angry GOP electorate. He never was a particularly charismatic politician; even when he challenged liberal activists in Wisconsin, he seemed preternaturally serene. His attempt to challenge a heckler at the Iowa State Fair by saying, “I won’t be intimidated!” was a belated attempt to show his toughness, instead of telling tales of his leadership in Wisconsin. The tough-talking rhetoric of Donald Trump and the in-your-face activism of Huckabee resonates more with conservatives who are looking for a street fighter to take on President Obama and Hillary Clinton.

At the same time, conservative voters are more interested in total political outsiders who never served in elective office than politicians who worked from within the system. It’s why Fiorina, whose resume is as establishment as any politician’s, can take off simply because she never won a political race. Walker, for all his successes, has essentially been a political lifer since college. (He didn’t even graduate in order to pursue his political interests.) As with four-term Texas Gov. Rick Perry, Walker found out that experience is more of a burden these days than an asset.

5. Rubio stands to benefit the most. Walker ended his campaign polling in the low single-digits, but his early withdrawal is more of a boon to Rubio than anyone else. Rubio and Walker started out competing against each other to be a viable alternative to Bush. It’s hard to see many Walker donors, staffers, and supporters moving to Bush’s campaign, given that dynamic. There’s a reason they didn’t get behind Bush the first time, when he looked like an establishment force.   

Rubio’s challenge is to consolidate the anti-Bush, establishment-oriented slice of the electorate. Walker, along with Ohio Gov. John Kasich, have been his biggest threats on that front. Now one potentially powerful rival is out of the picture.

One other consequence: The delegate-rich Midwestern primaries, where Walker looked to dominate, now are wide open. Even though he’s more moderate than Walker, Kasich is likely to make a play for the April 5 winner-take-all Wisconsin primary. And he's already working hard to organize for the March 8 Michigan primaries; Walker’s withdrawal may make his path a bit easier.

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