Obama leads Romney by four points: Poll

US President Barack Obama maintains a four point lead over Republican challenger Mitt Romney, a latest opinion poll has said.

The latest results, according to a leading media outlet, makes the Republican challenger within striking distance of the incumbent.

"A Democratic ticket featuring Obama and Vice President Joe Biden gets support from 48 per cent of registered voters, and a Republican ticket of Romney and new running mate Paul Ryan gets 44 per cent," according to the yesterday's NBC News/Wall Street Journal poll.

While the state of the US economy and the nation's direction continue to pose significant obstacles for the President, the poll points to even steeper challenges for Romney, including concerns about his tax returns and a lack of support for his plans to overhaul Medicare, NBC News reported.

"Mr Romney's choice of Rep Paul Ryan as his running mate has stirred excitement within the GOP that he can defeat the President. But the poll found little evidence the pick will affect the election, beyond helping unify Romney's conservative base," The Wall Street Journal said.

The survey of 1,000 registered voters, taken August 16-20, showed that significant swaths of the electorate harbour reservations about the former Massachusetts governor, concerns that have budged little since the general-election fight began in earnest four months ago, the financial daily said.

According to Wall Street Journal, Obama continues to receive low marks for his handling of the economy, particularly among undecided voters, who are more pessimistic than are voters overall about the country's economic future.

"Romney outscored the President on leadership qualities. He polled higher when those participating were asked which man has better executive skills, ideas to improve the economy and ability to change 'business as usual' in Washington," the daily said adding however since the spring, Romney has made scant headway in persuading the public that he understands the concerns of average Americans.

Meanwhile, another poll reported that Romney has a small lead in Wisconsin – the home State of his running mate Paul Ryan.

According to the results of the survey released by Public Polling Policy Romney has a 48 per cent to 47 per cent edge over Obama. It is a seven point swing from the national polling outlet's survey in early July, the Fox news reported.