Republican candidate Mitt Romney and his running mate Paul Ryan in a re-energized presidential campaign will on Monday, Aug. 13 try to persuade voters in two key states that they can restore America's economic might.

Romney is set to campaign in Florida while Ryan was heading to Iowa, both battleground states which may decide the outcome of the November presidential election.

With campaign battle lines re-forming, surrogates for Democratic President Barack Obama took to Sunday talk shows to cast Romneyand Ryan as bent on dismantling cherished entitlements like public health insurance and pensions for seniors.

But Romney and Ryan sought to portray themselves as the answer to a US economy struggling with high unemployment.

"I've got good news for you. And that is that this nation is going to come roaring back," Romney said with Ryan looking on, amid enthusiastic applause at a rally at a NASCAR stock car racing facility in North Carolina.

Romney attacked Obama as making the United States "more and more like Europe, with its "chronic high unemployment, low wage growth and fiscal calamity right at the door."

Ryan sought to make a clear contrast with Obama's team as he spoke to some 1,700 supporters inside the building while a swelling crowd of 4,000 waited outside, AFP reported.