Republican candidate Ron Paul refused Thursday to commit to backing Mitt Romney if the former Massachusetts governor becomes the party's nominee for president.

An anti-war candidate, Paul said he'd need more information about Romney's international agenda to make that decision.

"I'd talk to him and see what kind of a foreign policy he is going to have," Paul, a congressman from Texas, told reporters at a rally two days before most of Missouri's counties hold their Republican caucuses. "Mitt's a friend and we talk a lot. We just disagree on the issues."

Paul has pursued a strategy focused on caucus states, but he trails Romney, former Pennsylvania Sen. Rick Santorum and former House Speaker Newt Gingrich in the presidential race and has yet to win any of the states that have already voted.

Missouri's caucuses Saturday are the first step in a lengthy process of awarding the state's 52 delegates to the Republican National Convention. Paul so far has earned just 48 delegates, the least of the contenders, compared to Romney's 495 delegates, according to the latest count by The Associated Press.

Paul hit strongly on his anti-war theme while speaking to about 1,000 people at the University of Missouri's flagship campus. Romney and Santorum also campaigned in Missouri this week.

Paul shied away from naming any of his rivals but suggested they all want to plunge the U.S. deeper into military conflicts in the Middle East.

"They're just itching, the other candidates are saying, `When are we going to go get Syria? Why don't we start dropping bombs on Syria? When are we going to hit Iran?'" Paul said. "The Republicans are going to be in trouble unless they come our way and decide they want a president who's more for peace than for war."

He later added: "If you keep voting for warmongers, yes, this is going to be very negative."

Romney said last week that he was not prepared to support military action against Syria, where the government has cracked down on political dissent. Gingrich also has opposed sending U.S. troops or equipment to Syria.

Santorum has said he favors providing military equipment to the Syrian people but stopped short of backing airstrikes. Santorum has said he would order Iran's nuclear facilities be bombed unless they were opened for international arms inspectors. Romney has said he would combine diplomacy with "a military option" to stop Iran from acquiring nuclear weapons, including returning U.S. aircraft carrier groups to the nearby seas.

Paul told reporters Thursday that sanctions against Iran wouldn't work because they don't hurt the government.

"It hurts the people who are trying to change their government," he said.