Novi, Michigan (CNN) Gov. Scott Walker on Monday sought to use President Barack Obama's slipping popularity on foreign policy issues as a punching bag and sought to bolster his own credentials ahead of a likely presidential bid.

Speaking in Novi, Michigan, the Wisconsin Republican rallied around the plight of a Michigan man who has been held hostage in Iran since 2011 and blasted Obama for failing to do enough on the missing man's behalf -- as well as failing to ward off attacks by Islamic terrorists around the world.

Speaking at an Oakland County Republican Dinner, Walker listed terrorist acts committed by individuals affiliated with ISIS and others who sympathize with the group.

"That's something that worries you not just about places elsewhere around the world; you suddenly start to realize it's happened in France, in Belgium, in Canada. Lord knows what happened in the last day or so down in Texas and elsewhere around the country," he added. "You start to realize this isn't something we can just leave to page seven in the newspaper."