As President Obama tried to reinvigorate the ailing U.S.-Russia relationship Monday with a private chat with Vladimir Putin, the president's Republican opponent criticized the administration's entire "reset" policy as an "abject failure."

In an interview with Fox News, Mitt Romney said that policy -- in which the Obama administration has tried to nurture a more open and cooperative relationship with Moscow -- has stumbled.

"The Obama message to Moscow has been a reset policy, that somehow everything is warm and fuzzy between us and Moscow, and what we've seen over the last several years is that Moscow didn't get the message," Romney said. "The president's reset policy has been an abject failure."

Romney made the comments on the same day Obama met with Putin on the sidelines of the G-20 meeting in Los Cabos, Mexico. Following the meeting, Obama told reporters "tensions" between the U.S. and Russia "can be worked out."

The two leaders issued a joint statement touching on a host of issues, including the biggest area of tension -- Russia's support for Syrian leader Bashar Assad. The joint statement called for an "immediate cessation of all violence" and voiced support for a political transition to democracy.

Romney, though, threw cold water on the talk as he continued to assail Obama's foreign and domestic policies while on Day 4 of his six-state bus tour of battleground states -- where he and the president are virtually tied in most polls.

He campaigned in Wisconsin with House Budget Committee Chairman Paul Ryan, a possible vice presidential pick, and Gov. Scott Walker, whose triumphant recall election victory has inspired Republicans to aggressively target the state going into November.

During the interview with Fox News, Romney also joined the call for an independent counsel to investigate recent intelligence leaks to reporters. Other Republicans, as well as Sen. Joe Lieberman, I-Conn., have made that call in recent days.

"I do believe a special prosecutor should be looking into them," Romney said. "Those items should not be leaked in such a way that puts America's interest and our people in jeopardy."

Romney also would not rule out making a selection on his vice presidential choice well before the convention, as some Romney aides have suggested.

As for Syria, Romney was particularly critical of the Obama administration for tolerating Moscow's interference.

"This president has not communicated strength and resolve around the world," Romney said. "We need to make it very clear to Moscow that their interference in Syria poses a grave threat to the national interests of America, and to free people around the world."

Obama said Monday in Mexico that he and Putin agreed "that we need to see a cessation of the violence (in Syria) and that a political process has to be created to prevent civil war and the kind of horrific deaths that we've seen over the last several weeks."

Fox News' Carl Cameron and Jake Gibson contributed to this report.