However, the 68-year-old leader continues to maintain lead in some of the key battle ground states, other polls said.
The US presidential election slated to be held in November appears to have tightened as a series of latest national polls projected that Republican Donald Trump has gained some ground in the last week against Hillary Clinton of the Democratic Party.
Obama's national lead is now 2.1 point, RealClearPolitics said based on the average of all the recent national polls; the latest one being that of the Time magazine, according to which the US President now leads over Romney by five points in the most important battle ground state of Ohio.
CBS said Trump leads among white men, whites without a college degree, and seniors.
Various poll surveys ahead of the November 6 United States Presidential elections have come out with mixed results, indicating a possibly close contest between incumbent Barack Obama and his Republican rival Mitt Romney.
A week before the US presidential elections, Republican nominee Donald Trump has taken a slender lead of one percentage point against his Democratic rival Hillary Clinton for the first time since May in a major national tracking poll.
Likely voters who watched the first presidential debate are twice as likely to say the debate made them think better of Clinton than worse.
Another major media outlet for the first time projected Hilary's electoral college votes below the half way mark of 270.
"We don't know anything about Hillary in terms of religion," Trump told a group of evangelical leaders, adding, "she's been in the public eye for years and years, and yet there's no -- there's nothing out there."
Amidst reports that Donald Trump is gaining ground in key battle states in the US, the Republican presidential nominee on Thursday said that Americans are "ready to discard failed political establishment" that disrespects upon hardworking people.
The Democratic presidential nominee has gained a whopping 15 per cent national lead owing to the recent gaffes made by her Republican rival.
Analysts believe the main reason for Trump's popularity surge is that he now enjoys wider support from Republican voters after his decisive win in Indiana earlier this month.
Bernie Sanders alleged that Clinton is not qualified to be the president.
Locked in a neck-and-neck battle, Hillary Clinton and Donald Trump have made a last minute dash to key swing states to woo undecided voters as major polls on the final weekend before the election day showed the race for the White House was too close to call.