(CNN) -- Sen. Barack Obama's campaign directly questioned on Tuesday whether Sen. Hillary Clinton is prepared to be commander in chief.
Sen. Hillary Clinton has been on a campaign swing through Pennsylvania, which will hold its primary April 22.
In a memo released to reporters, Greg Craig -- a former Clinton administration official who is now an Obama adviser -- made some of Obama's sharpest attacks to date against the New York senator.
Craig wrote that Clinton uses "false charges and exaggerated claims to play politics with national security."
"When your entire campaign is based upon a claim of experience, it is important that you have evidence to support that claim," he wrote. "Hillary Clinton's argument that she has passed 'the Commander-in-Chief test' is simply not supported by her record."
Craig served as director of policy planning at the State Department during former President Clinton's second term. He was a top adviser to former Secretary of State Madeline Albright and served as counsel to former President Clinton during the impeachment hearings.
Clinton's campaign quickly responded with a memo of its own, saying Obama is "having his campaign issue a fundamentally misleading attack aimed at glossing over the doubts Americans have about his readiness to be Commander-in-Chief."
"After last week's defeats, the Obama campaign faced a choice: try to convince voters that Senator Obama is ready to take the 3 a.m. phone call in a positive way or try to tear down Senator Clinton's accomplishments," the Clinton memo also stated.
Clinton herself took aim at Obama at a campaign event in Harrisburg, Pennsylvania, referencing recent comments from some of his advisers that appeared to be at odds with his policy proposals. Watch Clinton question Obama's rhetoric »
"I've got to tell you, there's a big difference between talk and action, but if you're going to talk, then you ought to mean what you say so people can count on it," she told a cheering crowd.
Clinton was introduced by Pennsylvania Gov. Ed Rendell, who has campaigned with the New York senator during her two-day swing through the state that holds a crucial primary April 22.
Rendell told the crowd in Harrisburg, "She gets it. ... She understands exactly what's at stake for America and exactly how we have to get there."
Rendell said Monday night in Scranton that Clinton needed to campaign hard in Pennsylvania, particularly in places like Philadelphia, where Obama would do well and where she needed to "hold her own" in order to pull off a victory.
Rendell said he would welcome a "Clinton-Obama or Obama-Clinton" ticket as long as the party came together; he added that he would prefer for Clinton to get the top slot.
The Pennsylvania governor also spoke at length about his desire for Florida and Michigan to hold new primaries, one perhaps on June 14 and the other on June 28. He said he was open to mail-in contests but would prefer that voters actually be able to go to the polls.
Rendell and New Jersey Gov. Jon Corzine wrote an opinion piece in Tuesday's Washington Post, calling for a revote in Florida and Michigan and suggesting that the Democratic National Committee pay for it. E-mail to a friend