"They're (Republicans) just blankly asserting it and hoping it sticks. And the reason they're hoping it sticks is because the president has a very strong record on national security," Smith said in an interview. "His record makes that clear and the polls make it clear that people feel that way."
Kerry, D-Mass., the chairman of the Senate Foreign Relations Committee, said Republicans are "flailing around desperately trying to get some kind of handle, constantly trying to discredit the president, which doesn't serve our foreign policy or our national security."
Outside experts say the Obama administration has aggressively prosecuted leaks of classified information, charging six people under the Espionage Act for the alleged mishandling of classified information. Most notably is the case of Bradley Manning, a U.S. Army private accused of leaking hundreds of thousands of classified government documents, sending them to the secret-sharing website WikiLeaks.
"It's an astonishing prosecutorial record that goes far beyond what we've seen in previous administrations," said Steven Aftergood, an expert on government secrecy issues for the Federation of American Scientists, a private group.
Republicans have been ferocious in challenging Obama's foreign policy, accusing him of being wobbly in his support for Israel, uncertain as Syrians are slaughtered and lacking toughness as Iran pushes its nuclear program. They've criticized deficit-driven cuts in the military even though they agreed to them last summer. They've suggested he cut a secret deal with Russia that would undermine missile defense, an agreement that will emerge after the election.
Among Democrats, Obama's national security record has largely quieted any criticism among liberals, but it hasn't silenced them. They see policies even tougher than Bush that has paid little heed to the Constitution, international law or the sovereignty of other nations.
"This administration, as had the last administration, appropriated to itself the power to prosecute war anywhere it pleases in the world," said Rep. Dennis Kucinich, D-Ohio. "We cannot afford this financially, militarily or morally."
Putting party labels aside, Kucinich said that, while the Bush administration declared a global war on terror, "the Obama administration has kept those wars going and expanded the wars across Africa."
"We're propelling wars. What is this all about?" Kucinich said. "We don't have enough problems here at home ... We are promoting wars around the world, and so Democrat or not, I take strong exception to the direction our country has gone with respect to our international aggression."
Associated Press Deputy Director of Polling Jennifer Agiesta contributed to this report.
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