Obama, at George Mason University with just 18 days to go in the presidential campaign and polls showing Romney gaining, said the GOP candidate is trying to convince voters he didn't really mean it when he said he was the perfect Tea Party candidate.
"Now suddenly he's saying, 'What, who, me?' He's forgetting what his own positions are, and he's betting that you will, too," Obama said to laughter from the crowd of 9,000.
"I mean, he's changing up so much and backtracking and sidestepping, we've got to name this condition that he's going through. I think it's called 'Romnesia.'"
Obama, as he has since Wednesday, referred to Romney's tax and budget plans as a "sketchy deal," and said the Republican's social policies are "more suited to the 1950s," especially when it comes to women's issues.
Friday's Gallup daily tracking poll, which measures a seven-day rolling average, indicated the presidential race is a dead heat among registered voters with Romney favored by 48 percent and Obama, 47 percent. Among likely voters, however, Romney opened up a 6-point lead, besting Obama 51 percent to 45 percent. The poll put Obama's approval rating at 50 percent versus Romney at 48 percent. Disapproval of Obama rose two ticks to 46 percent, with Romney holding steady at 47 percent.
The poll queried 1,004 adults at least 18 years of age and has a 4 percentage point margin of error.