By Jeff Mason and Sam Youngman
PORTSMOUTH, N.H./ORANGE CITY, Iowa (Reuters) - President Barack Obama charged back onto the campaign trail on Friday and faced a withering attack from Republican rival Mitt Romney over disappointing new U.S. jobs numbers that dimmed the afterglow from Obama's Democratic convention.
Just hours after basking in his supporters' adulation in Charlotte, North Carolina, Obama was hit by a stark reminder of the challenge he faces convincing voters to give him a second term despite stubbornly high unemployment on his watch.
As the candidates launched the final two-month drive to Election Day, the latest Reuters/Ipsos poll showed Obama getting at least a small bounce from his convention, taking a narrow lead of 46 percent to Romney's 44 percent among likely voters. Romney had led 45 percent to Obama's 44 percent.
But the polling was conducted before the Labor Department reported on Friday that U.S. employers added a lower-than-expected 96,000 jobs in August - which could ensure that any "bump" in popular support for Obama is limited and brief.
The grim economic news followed Obama's impassioned speech on Thursday night in which he accepted his party's nomination and appealed to Americans for more time and patience to finish his economic agenda.
Pouncing on the jobs data to slam Obama's handling of the economy - the top concern of voters - Romney called the figures "disheartening" and "simply unimaginable" as he campaigned in Iowa.
"There's almost nothing the president's done in the last three and a half, four years, that gives the American people confidence he knows what he's doing when it comes to jobs and the economy," Romney said.
While noting that the private sector has now generated jobs for 30 straight months, Obama - returning to the campaign trail in New Hampshire - acknowledged that: "It's not good enough. We need to create more jobs faster."
At the same time, he pointed out that Republicans in Congress had blocked much of his jobs plan and accused Romney of making promises to revitalize the economy but not telling voters how he would do it.
"If the Republicans are serious about being concerned about joblessness we could create one million new jobs right now, if Congress would pass the jobs plan I sent them a year ago," Obama told a rally in Portsmouth, New Hampshire.
Obama's nationally televised acceptance speech capped two weeks of back-to-back nominating conventions for Obama and Romney.
The address opened the last phase of a White House battle that polls show is essentially deadlocked amid deep voter anxiety about the economy, which Obama argued he had put on the road to recovery even though growth remained lackluster.
Obama offered a steady-as-you-go message that outlined priorities like creating 1 million new manufacturing jobs but provided few details on how to achieve them. He thrilled the crowd when he ended with a preacher-like crescendo.
Pundits' reviews were not as glowing as they were for an address to the convention by former President Bill Clinton on Wednesday.
BACK TO CAMPAIGN TRAIL
The latest jobs data could give a boost to Romney, the former head of a private equity firm who has made his business experience the centerpiece of his campaign.
He argues he is uniquely qualified to create job growth and says Obama is not up to the job. But the Obama campaign has sought to undermine Romney's argument by pointing out some firms he invested in ended up cutting jobs or shipping them overseas.
Obama, who entered office during the darkest days of the 2007-2009 recession, has brought unemployment down from a peak of 10 percent in his first year but has been unable to crack the 8 percent barrier - a fact that Romney's camp has stressed.
"This is not even close to what a recovery looks like," Paul Ryan, Romney's vice presidential running mate, told CNBC.
Obama campaign spokeswoman Jen Psaki said the Romney-Ryan approach was not the answer, saying that would mean "going back to the same policies that led us to the crisis that we've been going through to begin with."
But the unemployment data still raises doubts whether Obama will get anything more than a limited -- and short-lived boost -- from the convention.
Obama senior adviser David Plouffe sought to play down expectations, saying he did not expect any major shift in voter sentiment. "We come out of the convention with momentum. That doesn't mean the race is going to change significantly," he told reporters traveling with Obama.
SWING STATE TOUR
Obama and Vice President Joe Biden on Friday were in the toss-up states of New Hampshire and Iowa for joint campaign events. Romney's schedule was also taking him to those two states, which could be critical to piecing together the 270 electoral votes needed to win the White House.
They are among eight to 10 battleground states that are likely to decide the election, a list that also includes Florida, Virginia, North Carolina, Ohio, Colorado, Nevada and Wisconsin.
Those states have been flooded by tens of millions of dollars in TV ads by the campaigns, and hundreds of millions more from outside groups allied with the two candidates.
Obama used his convention speech to acknowledge the economy was not fully healed while making the case that it was on the right track and he needed another term to finish the task.
Obama also dismissed Romney and Ryan as foreign policy neophytes and mocked the Republican nominee for offending British leaders by criticizing London's handling of the Olympic Games while on an overseas trip there.
Seeking to turn the tables on Obama, Romney said on Friday he had only been speaking to the British in a straight-forward way but faulted the president for what he said was a failure to talk tough enough with China about trade and currency practices.
"The message from last night was that the president's plan is four more years of the four last years. And I don't think the American people want four more years of the four last years," Romney said.
The Obama speech in many ways failed to capture the energy and excitement of his 2008 nomination in Denver. But Democrats said they were pleased with the three-day convention, which they say could help reignite supporters' enthusiasm.
With the conventions done - Republicans met last week in Tampa, Florida - the next big event on the political calendar is the first of three presidential debates on October 3 in Denver.
(Additional reporting by Margaret Chadbourn, Lucia Mutikani, Lisa Lambert; writing by Matt Spetalnick; Editing by Will Dunham and Jim Loney)