COLUMBIA, SC – MARCH, 19: Wisconsin Gov. Scott Walker speaks during a South Carolina GOP Grassroots luncheon at a Marriott hotel in Columbia, SC on Thursday March 19, 2015. (Photo by Jabin Botsford/The Washington Post)

COLUMBIA, S.C. -- At the start of Scott Walker's quest to be president, foreign policy has been a source of trouble. The Wisconsin governor has appeared shaky talking about world events and had to explain some perceived blunders.

But as Walker opened his first campaign swing across South Carolina here in Columbia on Thursday, foreign policy emerged as the highlight of his stump speech. Walker's sharp, rat-a-tat critique of President Obama's foreign policy record drew a sustained and boisterous standing ovation from the crowd of 150 Republican activists at a party luncheon.

"It bothers me looking ahead that we’ve got a president right now who draws a line in the sand and allows people to step forward," Walker said. "A president who seems to call ISIS the JV squad, Yemen a success story, Iran a place we can do business with. His former secretary of state [Hillary Rodham] Clinton gave a reset button to Russia -- a reset button!"

Walker said the United States needs a commander in chief who will stand more strongly against Islamic State terrorists and behind Israel.

“We need a leader in America who will once and for all stand up and affirm that Israel is an actually an ally of ours," Walker said. "We need a leader who will look the American people in the eye and say we will do whatever it takes – whatever it takes – to make sure that radical Islamic terrorism does not wash up on American soil. I’d rather take the fight to them.”

[Walker: Reagan’s bust of air traffic controller strike his ‘most significant foreign policy decision’]

Walker is in South Carolina, home to the first presidential primary in the South, for two days of events throughout the state ahead of the expected launch of his 2016 presidential campaign. He is headlining four grassroots events sponsored by the South Carolina Republican Party and is meeting privately with key GOP activists whom he hopes may join his campaign.

Following his Columbia luncheon speech, Walker met with Gov. Nikki Haley (R) at the Governor's Mansion, and was scheduled to also visit with state legislators.

In his remarks here, Walker spoke about his battles with labor unions in Wisconsin. “They were seeking to intimidate us," he said, noting that protesters banged drums at the state capitol, targeted his sons on Facebook and shouted at his parents at the grocery store.

Walker stressed to the gathered activists his record of governing as a conservative. He talked about turning the state's $3.6 billion budget deficit into a surplus, overhauling state regulations, defunding Planned Parenthood and signing laws that expand gun rights and require voters to show photo identification at the polls.

And, as he did in recent visits to Iowa and New Hampshire, Walker talked about growing up with little means as the son of a preacher father and part-time secretary mother.

“We didn’t inherit a lot from our family," Walker said, a veiled contrast to his top challenger in the Republican field, Jeb Bush, a former Florida governor and son and brother of past presidents.