Last week's Democratic National Convention helped President Obama improve his standing against Republican Mitt Romney, according to a new Washington Post-ABC News poll, but did little to reduce voter concern about his handling of the economy.

The survey shows that the race remains close among likely voters, with Obama at 49 percent and Romney at 48 percent, virtually unchanged from a poll taken just before the conventions.

But among a wider sample of all registered voters, Obama holds an apparent edge, topping Romney at 50 percent to 44 percent, and has clear advantages on important issues in the campaign when compared with his rival.