"My takeaway is that it's pretty decent news for Obama that his bump is sustaining so long and he may be turning the post-convention bump into a lead," said Ipsos pollster Julia Clark.
In a shift in recent days, Americans also gave a small edge to Obama on the crucial topics of jobs and the economy, as they feel less nervous about economic conditions.
Thirty-seven percent of registered voters thought Obama had a better plan for the economy, compared with 34 percent who favored Romney on the issue. Obama led 36 percent to 35 percent on the issue in a poll released last Thursday.
Forty percent backed Obama on jobs and employment, compared with 36 percent who favored Romney.
"This is a bit of a shift," Clark said. The two candidates had been tied or Romney was slightly ahead on the economy since May, but that has changed to give Obama a small edge in the wake of the convention.
"People are not really quite as nervous about the economy as they were a couple of months ago," Clark said.