Muslims belonging to the radical Shi'ite sect in both Iran and Iraq believe that the "end of the world is going to come within their lifetime" because their regime preaches an "apocalyptic version" of Islam, Republican US presidential hopeful Rick Santorum said during the second Republican presidential debate in California on Wednesday.

He expressed concern that these Muslims, whom he called a "death cult," will now have the means to acquire a nuclear weapon as a result of the Iran nuke deal made by President Barack Obama, giving them the means to fulfill their vision of the apocalypse.

Santorum said around two-thirds of Iranian and Iraqi Shi'ite Muslims "believe in bringing about the end of times," noting that this is "their theological goal, and we are in the process of giving them a nuclear weapon to do just that."

"Yes, they're radical Islamists, that's true. But they're a particular version of it, which is an apocalyptic version, which is a death cult," he said.

Santorum, a former US senator from Pennsylvania, is lagging behind in the race for the Republican presidential nomination.

During the debate, Santorum seemed to set himself apart from other Republican candidates when he expressed an openness to increase the country's minimum wage, around 50 cents per year in a period of three years.

"To me, if you're going to talk to 90 percent of American workers—by the way, 90 percent of American workers don't own a bar. They don't own a business. They work for a living. They're wage—most of them are wage earners," he said. "And Republicans are losing elections because we're not talking about them. All we want to talk about is, what happened to our business? There are people who work in that business."