Wisconsin Gov. Scott Walker (R) speaks at the winter meeting of the Club for Growth on Feb. 28, 2015, in Palm Beach, Fla. (Joe Skipper/AP)

Wisconsin Gov. Scott Walker on Sunday staked out a hard-line stance against a path to citizenship for undocumented immigrants, saying "flat out" that he has shifted on the issue since 2013, when he supported it.

"I don't believe in amnesty, and part of the reason why I've made that a firm position is I look at the way this president has mishandled this issue," Walker (R) told Chris Wallace on "Fox News Sunday." "I think the better approach is to enforce the laws and to give employers, job creators the tools like e-verify and other things to make sure the law is being upheld going forward."

Wallace pressed Walker — who is weighing a presidential bid in 2016 — on his opposition to comprehensive immigration reform, pointing out that the governor had said in a 2013 interview with a Wisconsin editorial board that he supported it.

Walker insisted Sunday that border security was an important first step to repairing the United States' flawed immigration system.

"But you said you supported" comprehensive reform, Wallace insisted.

"And my view has changed. I'm flat out saying it. A candidate can say that. Sometimes they don't," Walker said.