Without a knockout blow in Pennsylvania, Barack Obama is going to have to keep jabbing back at Hillary Clinton. But those counterpunches could hurt his campaign, warns Jonathan Weisman in the Washington Post. The Obama camp's swing to the negative in the closing days of the Pennsylvania campaign shows he can take on John McCain—but at the same time undercuts his message of fresh hope and an end to old-style politics, writes Weisman.
Obama advisers admit his image may been tarnished in recent days—but say he was compelled to respond to attacks. One Democratic insider speculated that with the Indiana vote coming up—a contest even Obama has dubbed a "tiebreaker"—the candidate will likely stay on the offensive, relying on scandals that broke during Bill Clinton's White House.