President Barack Obama will this week look Americans in the eye and say he deserves four more White House years despite national economic despondency and disappointed hopes stretching back to 2008.

He needs to counteract the message that Romney and Ryan impressed on voters that he has done nothing, that his time is up and that he has disappointed Americans

With his job in peril, Obama will use the Democratic National Convention to counter the cutting Republican charge that though his election was historic and rightly celebrated, his presidency is a bust.

The first African-American President will insist that votes of star-struck supporters four years ago were not a waste, despite what his Republican foe Mitt Romney says.

“Those who oppose change have always bet on your cynicism,” Obama told a young crowd in Virginia last week in a possible preview of his convention tone.

“They always bet on a lack of hope – and throughout American history, they have lost that bet.”

But Obama has said he believes that despite his reputation as a soaring speechmaker, he has not adequately communicated to voters the stakes and achievements of a term haunted by economic crisis.

Republicans simply ask: what achievements?

So Obama’s prime time convention address in Charlotte, North Carolina, on Thursday represents a priceless chance to reset the political narrative two months before Americans vote in a race currently too close to call.

Job number one: rebut the anti-Obama rhetoric pumped out by Romney and his running mate Paul Ryan last week in Florida.

“The President does have some work to do in Charlotte after the Republican convention,” said Mich­ael Kramer, a professor specialising in presidential communications at St Mary’s College.

“He needs to counteract the message that Romney and Ryan impressed on voters that he has done nothing, that his time is up and that he has disappointed Americans.”

Romney’s most effective charge was that Obama, despite vowing to reverse the rise of the oceans and heal the planet, simply did not deliver what Americans care most about: economic prosperity.

“You know there’s something wrong with the kind of job he’s done as President when the best feeling you had was the day you voted for him,” Romney said, in the sorrowful manner of a father figure admonishing a younger man.

Vice-presidential nominee Ryan surely stung Obama when he tweaked the President’s self-created image as the personification of hope and change.

“College graduates should not have to live out their 20s in their childhood bedrooms, staring up at fading Obama posters,” Ryan said.

Leila Brammer, professor of communications and rhetoric at Gustavus Adolphus College, Minnesota, said the Republican critique resonated with swing voters and Obama needed to do more than defend his administration and talk economics.

“He really has to find a way to strike an emotional chord,” she said, of a President who once promised to unite a nation that seems ever more divided four years after he won power.

“People are disappointed in him. They are not only focused on the economy. They are also saying, ‘we had faith in this guy, it was almost a religious faith, and he has let us down’,” she said.

Obama will try to revive the old magic on Thursday by, as he did in 2008, leaving the confines of a convention hall for a huge outdoor foot-ball stadium packed with 70,000 people.

He will defend his crusade for change, highlighting his historic health care reform and his orders to end the ban on gays serving openly in the military, to halt the Iraq war, to decimate Al-Qaeda and kill Osama bin Laden.

Obama will frame his record and call for higher taxes on the rich and to safeguard health care for the elderly, as more sympathetic to the middle class than that of multi-millionaire Romney.

“The message we want to hammer home is that this President is committed by experience, by belief and wholeheartedly to rebuild an economy in which every person who works hard can get ahead, in which the middle class is secure,” said Obama aide David Axelrod.

The President has a strong support cast.

Popular First Lady Michelle Obama will laud him as a man and a leader. Ex-President Bill Clinton, remembered for steering a more prosperous age – will also make the case for four more Obama years.

Obama goes into his convention starting today with significant political advantages.

He is seen as more likeable, stronger on foreign policy and more sympathetic to the middle class than Romney, meaning all may not be lost for a presidency that Ryan claims is adrift, trying to sail on “yesterday’s wind”.

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