Clinton escalated her attack on Obama’s qualifications to be president on Saturday, arguing that both she and the presumptive Republican nominee, McCain, could offer voters a “lifetime of experience” while Mr. Obama could only hold out his 2002 speech opposing the Iraq war. ... Mr. Obama, meanwhile, mocked Mrs. Clinton’s credentials as a self-professed agent of change, saying she had come down on both sides of the Nafta trade deal and criticizing her reasoning for voting in 2002 for the invasion of Iraq. “Real change isn’t voting for George Bush’s war in Iraq and then telling the American people it...