President Obama has a 4-percentage-point edge over Mitt Romney among likely voters in Ohio, a must-win state for both sides, a CNN/ORC International poll released on Tuesday shows.
The poll found 51 percent of likely voters backed Obama and 47 percent supported Romney in a head-to-head matchup. The survey of 772 likely voters -- conducted Oct. 5-8 after the first presidential debate -- has a margin of error of plus or minus 3.5 percentage points.
It also found that 85 percent of likely voters have made up their minds about which candidate to support, with just 13 percent saying they might change their minds.
Both candidates are heavily invested in winning Ohio, which is regarded as the biggest battleground prize. Until last week, Obama had held a decisive advantage in polls, a development attributed to his support for bailing out the automobile industry, which is a major employer in the state. But Romney's strong debate performance has turned the race into a statistical dead heat in some recent surveys.