Rice: United States' "voice is muted" under Obama

(CBS News) Former Secretary of State Condoleezza Rice on Wednesday said that it's time to change leadership in the White House in order to restore American leadership on the world stage.

"There is no doubt the United States' voice has been muted," Rice said on "CBS This Morning," adding, "When the United States' voice is muted, the world is a more dangerous place."

At a time when Syria is "butchering" its people and Iran is aiding, Rice said, the United States should stop relying on the United Nations Security Council to act.

"No one says we should be treating Syria as if it needs American boots on the ground," Rice said, but there should be a "clear message that gets over the objections of the Russians and the Chinese. When the United States says Assad must go and then nothing happens to make Assad go, the U.S. has a credibility problem."

Rice said the U.S. should "leave the Security Council aside" and instead work on arming the Syrian opposition in a way that is in accordance with a political plan. Under President Obama, she said, there's no evidence that's happening.

The former George W. Bush administration cabinet official is slated to speak at the Republican National Convention in Tampa, Fla., where Mitt Romney will formally accept the Republican presidential nomination this week.

"A President Romney, I think, would understand American exceptionalism," she said, and "would not be afraid to lead from in front."