Obama's lead in the new Columbus Dispatch poll is within the 2.2 margin of error.
Forty-two percent of likely voters in Iowa have cast ballots, with Obama leading by 22 points among early voters.
President Obama has a six-point advantage in Ohio, according to a new Wall Street Journal/NBC News/Marist poll.
President Obama tops 50 percent and continues to lead Mitt Romney in Michigan, according to the latest Rasmussen survey of likely voters.
Rasmussen is not the only poll to show the president making incremental gains on Romney nationally.
The Reuters polls show a close race in all four states; the greatest margin is Obama's 5-point lead in Virginia.
President Obama has a small lead over Mitt Romney in Colorado, according to a CNN-ORC poll released Thursday.
A new poll of Iowa shows Mitt Romney opening a 1-point lead in the state, evidence that the Republican challenger could be making headway in the crucial battleground state. But two other surveys also released Thursday gave President Obama an advantage, suggesting that the Rasmussen survey favoring Romney could be an outlier — although all three of the polls suggest momentum could be shifting in the Republican nominee's favor.
The Rasmussen poll, the most favorable of the pair to the Republican presidential candidate, gave Romney a 49-48 percent advantage in the Hawkeye State. That's a 1-point improvement for Romney over a 48-48 percent split in the same poll released just over a week prior.
But Rasmussen's likely-voter screen has consistently shown a rosier picture for Romney than other surveys of the state, a trend that remained true on Thursday. A WeAskAmerica poll also released Thursday gave President Obama a 49-47 percent advantage, good for a 2-point lead in the state. But in an encouraging sign for Romney, that again represented a single-point swing in his favor from the last poll conducted by that firm in the state, a mid-October survey that gave the president a 49-46 percent advantage.
The latest round of swing-state polls show a number of battlegrounds remain a toss-up.
Independents favored Romney by 7 points, and those "extremely" interested in the race backed the GOP nominee, 53-42.