The poll showed Arizona Sen. McCain, who has clinched the Republican presidential nomination, is benefiting from the lengthy campaign battle between Obama and Clinton, who are now battling to win Pennsylvania on April 22.
McCain leads 46 percent to 40 percent in a hypothetical matchup against Obama in the November presidential election, according to the poll.
That is a sharp turnaround from the Reuters/Zogby poll from last month, which showed in a head-to-head matchup that Obama would beat McCain 47 percent to 40 percent.
“The last couple of weeks have taken a toll on Obama and in a general election match-up, on both Democrats,” said pollster John Zogby.
Matched up against Clinton, McCain leads 48 percent to 40 percent, narrower than his 50 to 38 percent advantage over her in February.