Charlotte (North Carolina): US President Barack Obama and his Republican challenger Mitt Romney are virtually tied up in the run up to November presidential elections, latest opinion polls have shown.
According to a new survey conducted by CNN/ORC International, both Obama and Romney are tied at 48 per cent.
The polls were conducted after last week's Republican National Convention in Tampa, Florida and before the start of the Democratic National Convention which started yesterday.
Both the CNN and another poll conducted by Gallup said that Republican National Convention did not yield much advantage to Romney as had been the case earlier.
"The Republican convention had at best a mild effect on the presidential race, and from a statistical viewpoint, no effect at all," CNN's Polling Director Keating Holland said.
"Demographically, Romney's overall one-point bounce masks some movement among subgroups and suggests that Romney's pitch to some groups may have worked but at the expense of turning off another group of voters," Holland said.
Gallup said that Romney received no bounce from last week's Republican National Convention, as the 46 per cent of registered voters who supported him in August 31-September 3 Daily tracking is essentially the same as the 47 per cent who preferred him in August 24-27 tracking, the four days preceding the convention.
Past presidential nominees have seen their support among registered voters increase five points on average after their party's nominating convention, according to Gallup's review of the history of convention bounces going back to 1964.
Romney becomes one of three recent nominees -- and the first Republican -- who did not receive a convention bounce, joining George McGovern in 1972 and John Kerry in 2004.
Both McGovern and Kerry, like Romney, challenged incumbent presidents, with McGovern suffering a landslide defeat to Richard Nixon and Kerry losing a close election to George Bush.
Real Clear Politics which keeps tracks of all the national opinion polls says that Obama has a lead of 0.1 per cent over Romney if the average of all the polls is taken.