In Iowa, which has six electoral votes, Obama has an edge over the Republican challenger Mitt Romney among likely voters, 47 percent to 42 percent, according to a Des Moines Register Iowa Poll.
The race for four electoral votes in New Hampshire is a dead heat, according to the WMUR Granite State Poll. Obama and Romney are tied at 47 percent among likely voters, the poll showed.
When asked towards whom they are leaning, the state's small number of undecided likely voters are evenly split, CNN reported.
Earlier two samples of Ohio, including a CNN/ORC International poll, showed Obama had an advantage in Ohio. In Florida, one poll showed Romney with an advantage and another showed Obama had an edge.
Just over four in ten Iowa voters have already cast ballots, and Obama has a 22 point lead among those who have voted early.
The poll also shows Romney with an eight point advantage among those who plan to cast ballots on Election Day, and that early voting has been lighter among the more Republican areas in the state's Northwest.
Obama, whose win in the 2008 Iowa caucuses put him on his way to the Democratic nomination and the White House, is scheduled to headline his last campaign rally in Des Moines Monday, before flying to Chicago where he will watch the results.
"Iowa, I started my presidential journey right here in this state. After two years of campaigning and after four years as president, you know me by now," Obama told about 5,000 supporters Saturday in Dubuque. "You know I tell the truth. And you know I'll fight for you."
Romney started the day telling New Hampshire voters that they should vote for him "for love of country," and not revenge.
His comments came in response to Obama, who told supporters yesterday not to boo Romney's name at rally in Springfield, Ohio. "No, no, no -- don't boo, vote," Obama said. "Vote. Voting is the best revenge."
He closed it in Colorado, a state Republicans have long described as favourable ground. "The only thing that stands between us and some of the best years we've ever know is lack of leadership," he told 17,000 cheering supporters in Englewood.
