US President Barack Obama still led Republican challenger Mitt Romney in this year's key battleground Ohio, which could be decisive for the Election Day outcome, but the margin has been narrowed to five points in a latest poll released on Monday.

The new poll, co-conducted by Quinnipiac University/CBS News, found Obama held a 50 to 45 percent lead over Romney among likely voters in the state of Ohio, down from a 10-point advantage nearly a month ago. Three percent of likely voters surveyed said they were still undecided.

Obama held a double-digit lead over Romney among women by 55 percent to 40 percent. The margin was also narrowed sharply from a poll in September where Obama led Romney among female voters by 60 percent to 35 percent.

On the top issue of this election cycle, the two candidates were now even on handling the economy where the president led by 6 points last month. On foreign policy, the focus of the two candidates' third and final face-off on Monday night, Obama currently led Romney by 50 percent to 43 percent, where the incumbent's advantage used to be as large as 13 percentage points.

At the same time, Romney widened his lead over Obama among independent voters of Ohio, now by seven points, 49 to 42 percent. He had only one point edge over Obama in September.

In response to the findings of Obama's shrinking advantage, Stephanie Cutter, deputy manager of the Obama campaign, said on CNN that the campaign was "very pleased" by the current lead.

Both Obama and Romney campaigns have long seen Ohio, one of the 12 swing states, as the crucial battle ground towards the Election Day victory and thus spent considerable time and resources campaigning in the state. Both candidates have remained as regular visitor to the state particularly as the election geared up towards the final showdown in November.

According to the White House, Obama will fly to Ohio to campaign on Tuesday following his final debate with Romney.