WASHINGTON — Three of the four Republican presidential candidates said the United States should make a more explicit threat of military action against Iran.

Mitt Romney, Rick Santorum and Newt Gingrich agreed in the CNN debate on Wednesday in Arizona that the measures taken by President Obama to isolate Iran have not gone far enough. 

“This is a president who has made it clear through his administration in almost every communication we’ve had so far that he does not want Israel to take action, that he opposes military action,” said Romney, the former governor of Massachusetts, to nods of agreement from Santorum and Gingrich. “This is a president who should have instead communicated to Iran that we are prepared, that we are considering military options. They’re not just on the table. They are in our hand.”

Obama has hewed to language first expressed by his predecessor, George W. Bush in 2006, that “all options are on the table” when it comes to Iran, and has refused to make the threat any more explicit, although Israeli leaders have become more pronounced in threatening a strike.

“I do believe there are moments when you pre-empt,” said Gingrich, the former speaker of the U.S. House of Representatives, answering a question about whether he would give Israel the go-ahead for a pre-emptive strike. “If you think a madman is about to have nuclear weapons and you think that madman is going to use those nuclear weapons, then you have an absolute moral obligation to defend the lives of your people by eliminating the capacity to get nuclear weapons.”

The three candidates also said the Obama administration should do more to bolster the opposition in Syria, in part because it is Iran’s proxy.

U.S. Rep. Ron Paul (R-Texas) dissented, saying the war with Iran that would likely ensue from a strike would be a moral, constitutional and economic disaster.

“Ask the people and ask the Congress for a declaration of war,” Paul said. “This is war and people are going to die. And you have got to get a declaration of war.”