AP

WASHINGTON CHALLENGER Mitt Romney and President Barack Obama are hammering each other on the economy, battling over an issue that is foremost in the minds of Americans and the one that will determine how they cast their ballots in the November election.

Romney says Obama has botched the recovery from the Great Recession. Obama says his opponent would just make matters worse.

It has only been two weeks since Romney emerged alone from the long and bitter primary fight with fellow Republicans and is trying to unite an increasingly conservative party base behind his candidacy.

The prolonged Republican battle reflected the difficulty Romney had in winning conservative backing, given the moderate positions he held a Republican governor in overwhelmingly Democratic Massachusetts.

“Obama is over his head and swimming in the wrong direction,” Romney said on Wednesday in a scorching speech delivered across the street from where the president will deliver his Democratic National Convention acceptance speech in September.

Nationally, the unemployment rate has dropped from 9.1 percent last August to 8.2 percent in March, the lowest since about the time Obama took office. But job growth has been weak, millions of people remain unemployed and improvements in hiring haven’t translated into higher salaries for those who are working.

“Even if you like Barack Obama, we can’t afford Barack Obama,” the Romney said in an evident reference to the president’s ability to transcend at least some of the public’s dissatisfaction with the pace of the economic recovery.

Obama laid out his case for re-election in Ohio, a key battleground state that can vote either Democrat or Republican.

Between 2000 and 2008, Republican policies produced “the slowest job growth in half a century and we’ve spent the last three and a half years cleaning up after that mess,” Obama said.

He later went on to Michigan, another key industrial state, for some fundraising.

Speaking in a museum named for the founder of Ford Motor Co, he got some of his biggest cheers when he highlighted his administration’s efforts to rescue the American auto industry.