Sen. John McCain, R-Ariz., said Sunday the White House was disappointingly low-key in its support of Syrian rebels and political dissidents in Iran.
"This leading from behind is not going to work, my friend," McCain said on ABC's "This Week."
McCain said the United States was not only losing its leadership role in promoting democracy and human rights but was also allowing the momentum of pro-democracy movements to flag.
McCain, who lost to Obama in the 2008 election, advocated a more robust plan for getting dissident Chen Guangcheng out of China and pushing Iran out of Syria where it has been a key supporter of President Bashar Assad.
McCain said the United States should be both arming Syrian rebels and at the same time supporting opposition groups inside Iran.
"How could we sit by and watch this slaughter [in Syria] go on, while the president of the United States is totally silent?" McCain said.
White House political adviser David Axelrod said the winding down of the U.S. combat presence in Iraq and the elimination of Osama bin Laden was evidence Obama was not sitting on his hands in terms of national security matters.
Axelrod also pushed back on criticism of the ongoing Chen dispute, saying Republican Mitt Romney's campaign was not privy to crucial behind-the-scenes information about the situation.
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