US President Barack Obama received a significant popularity bounce from his party convention last week and now leads the White House race by a small but clear margin, polls indicated.
One polling expert working for Republican challenger Mitt Romney dismissed the convention bump as a "sugar-high" that would dissolve once the harsh realities of the president's failed economic policies have sunk back in.
But a CNN/ORC survey of likely voters gave Obama 52 percent of the vote compared to 46 percent for Romney, who also fell behind in August in terms of fundraising, the first time he has trailed in the cash race since April.
A Gallup seven-day tracking poll out Monday also showed Obama ahead, with a five percentage point cushion, while another post-convention survey gave the Democratic incumbent a five-percent lead in the key battleground of Ohio.
The candidates were tied at 48 percent support in the previous CNN/ORC poll, conducted before last week's three-day convention in Charlotte, North Carolina, at which Obama was formally nominated for a second term.
At the convention's finale, Obama shed the soaring rhetoric he used four years ago and portrayed himself as battle-hardened, demanding patience from an electorate he said faced the starkest choice in a generation.
Former president Bill Clinton's speech the night before, defending Obama's handling of the economy and drawing stark contrasts with the top-down approach of the Republicans, was widely seen as having given him an important lift.
Hours before the results of the CNN/ORC poll were known, Romney's team was already seeking to reassure donors and supporters, issuing a "State of the Race" bulletin that betrayed nerves in the campaign.
"Don't get too worked up about the latest polling. While some voters will feel a bit of a sugar-high from the conventions, the basic structure of the race has not changed significantly," said Romney pollster Neil Newhouse.
"The reality of the Obama economy will reassert itself as the ultimate downfall of the Obama presidency, and Mitt Romney will win this race," his missive went on to say.
Newhouse argued that Romney was still the preferred candidate on the crucial issue of the economy and that all the signs pointed to a tight race in which the former Massachusetts governor had a money advantage.
The message was seen as an attempt to shore up support for the Republican candidate after some disappointing polls and after Obama outraised Romney in August by $114 million (92 million euros) to $111 million.
Newhouse said Romney's supporters were more enthusiastic and that the campaign had crossed a 20 million volunteer threshold as they deploy an all-out "Ground Game" across the key swing states in the November 6 election.
"Mitt Romney will be the next president," he insisted.
"The outcome of this race will ultimately be determined in favor of governor Romney because he has the better leadership skills, the better record, and the better vision for where he wants to take the country."
Speaking at a campaign event later Monday in Ohio, Romney made no mention of the disappointing poll numbers as he hammered Obama over his stewardship of the economy -- insisting again on Obama's weak record on job creation.
While some parts of the US economy have begun to show signs of life, and the stock market has more than recovered since the crash that struck shortly before Obama's election, unemployment remains doggedly high, above eight percent.
"We know what would happen if he were re-elected, we'd see more years of high unemployment, we'd see more years of massive deficits, we'd see more years of almost no wage growth in this country," Romney said.
"We'd see more years of a nation at the cusp of the kind of crisis you're seeing in Europe. We're forewarned and that's why we're not going to re-elect this man," he blasted.
Obama had no campaign events planned Monday.
The all-important first presidential debate between Obama and Romney in Denver, Colorado is now less than a month away on October 3. The rivals will hold two more face-offs on October 16 and October 22.
Vice President Joe Biden and Romney running mate Paul Ryan hold a one-off debate on October 11.
