Navy SEAL unloads in his new anti-Democrat ad

In the final days before Missouri’s Republican gubernatorial primary, candidate Eric Greitens responded to a Democratic attack ad by firing more than 100 rounds from a machine gun as an announcer declared in a rebuttal ad that he would bring out “the big guns” to “fight Obama’s Democrat machine.”

Greitens, a former Navy SEAL, prevailed in a hard-fought, four-way primary Tuesday, earning the right to face Democratic Attorney General Chris Koster in a Nov. 8 gubernatorial election. The race features many of the same undercurrents as the presidential campaign between Republican businessman Donald Trump and Democratic former Secretary of State Hillary Clinton.

Like Trump, Greitens portrays himself as a macho outsider ready to blow up politics as usual. And the early attack ad hinted that the brash Greitens is perhaps the one Republican that Koster, who carries decades of political experience, least wanted to face.

Greitens, 42, of St. Louis, has a remarkable resume. He’s been a Rhodes scholar, White House fellow, boxer, martial arts expert and best-selling author. He has traveled the world as a photographer on humanitarian missions documenting the conditions of war refugees and homeless children. He joined the Navy in 2001, just months before the Sept. 11 attacks, and later was chlorine-gassed in a suicide bomb attack in Iraq.

After his military career, he founded The Mission Continues, a nonprofit that connects veterans with volunteer work to ease their transition back home. Greitens developed a nationwide network of donors for the organization, some of whom have helped finance his gubernatorial campaign.

Greitens won the split Republican primary with less than 35 percent of the vote. Many voters interviewed by The Associated Press said they were drawn to Greitens by his outsider’s call to shake up the political establishment.

“I think if we were able to measure it, we’d find that a lot of the Trump voters in the spring were Greitens voters in the August primary,” said Dave Robertson, a political science professor at the University of Missouri-St. Louis.

Greitens and the other GOP candidates sought to tap into anger among some conservatives about the handling of several racial incidents in the state.

The candidates sharply criticized the way Democratic Gov. Jay Nixon responded to riots following the 2014 fatal police shooting of Michael Brown in Ferguson and to protests over racial concerns last fall at the University of Missouri in Columbia.

Greitens was particularly dismissive of the student protesters, comparing them with the young military members he served with in Iraq and Afghanistan.

“I find it a little hard to hear when I hear students complaining that life on campus is just too tough,” Greitens said during debates.

Greitens set up a committee for a potential gubernatorial run just days before the Feb. 26, 2015, suicide of Missouri Auditor Tom Schweich, another gubernatorial candidate. Though Greitens had no role, Schweich had believed that other Republicans were turning against him with negative attacks and rumors. His death led to at least temporary calls to tone down negative campaigning.

The Associated Press contributed to this article.