Finally, the Clinton team suggests that Obama's background has not been fully "vetted," making him a risky nominee, whereas Clinton's past, her aides say, is an open book. "There is not another shoe in her closet to drop," says Clinton adviser Harold Ickes.
While her campaign sharpens its attacks, Clinton plans to stage more events showing her more likable side. She was pleased with her appearances on Saturday Night Live and Jon Stewart's The Daily Show, which demonstrated her sense of humor.
One new issue that Clinton hopes to raise in the next big primary—Pennsylvania, April 22—is Obama's position on gun control. Critics say he was tougher on guns as an Illinois legislator than he is now, trying to court pro-gun voters. In attacking those alleged contradictions, Clinton would be taking the approach s he did in challenging Obama's views on the North American Free Trade Agreement, a strategy that appeared to damage him in Ohio.
Obama continues to do well with young voters, African-Americans, men, and college graduates, and he also plans to get more aggressive. If he does, voters could see the strategy as a desperate, hypocritical gambit by a man who bills himself as an advocate of conciliation. But his supporters say Obama needs to get more negative to show that he has the stomach for the rough tactics that Democrats expect in the campaign against Republican John McCain.
Some Obama strategists have identified likely lines of attack, including Clinton's failure to release her tax returns, and the granting of special access to big contributors while her husband Bill Clinton was president. David Axelrod, Obama's chief strategist, signaled that the campaign will especially emphasize the tax-return issue. He said the public has a right to know the Clintons' tax rate, their sources of income, and any use of tax shelters.
For now, though, the momentum belongs to Clinton. "Hillary is a fighter," says Sen. Charles Schumer of New York. "You never count her out." The same might be said of Obama, which helps to explain why the race is so close, and why there is no end in sight.