(CBS News) Presumptive Republican presidential nominee Mitt Romney is back in the U.S. after a week-long trip abroad - and on the attack against President Obama.
He have refrained from attacking the president directly while he was overseas, but now that he's back on U.S. soil, he's making up for lost time.
Both men are campaigning in battleground states, accusing each other of crafting plans that would wreck the economy.
On Thursday, Romney was in Colorado, talking about jobs and the economy. In his first campaign stop since getting back, Romney issued a failing grade to the Obama administration.
"I've got a little report card here," he said at one stop.
He called it a "presidential accountability scorecard" and passed it out to a group of more than 1,000 in Golden, Colo. The card flunked Mr. Obama on everything, from jobs creation to home prices and the deficit.
Going through them, Romney said, "Finally, we have family income, that's gone down; all measures he laid out are measures that have gone in the wrong direction."
But in Winter Park, Fla., President Obama said it was Romney who needed to retake Economics 101, after a non-partisan tax policy group panned Romney's tax plan, saying it would drive up the national debt by hundreds of billions of dollars - and would only benefit the rich.
"They have tried to sell us this trickle-down tax cut fairy dust before," Mr. Obama said. "And guess what? It didn't work then and it will not work now."
The Obama campaign is also not letting up on Romney's refusal to release any more than two years of his personal taxes.
It unveiled a new ad in eight battleground states in which the announcer says, "Mitt Romney made $20 million in 2010 but paid only 14 percent in taxes. Probably less than you," the ad suggests.
And Senate Majority Leader Harry Reid, D-Nev., made an explosive accusation about Romney, right on the Senate floor, saying, "The word's out that he hasn't paid any taxes for 10 years. Let him prove that he has paid taxes, because he hasn't [proved it]."
But Reid didn't provide any evidence for that claim, and Romney laughed it off in an interview with conservative host Sean Hannity on Hannity's radio show, saying, "It's time for Harry to put up or shut up. Harry's gonna have to describe who it is he spoke with because, of course, that's totally and completely wrong."
But Romney's top campaign advisers aren't laughing. They likened Reid's charge to the McCarthy witch hunts of the 1950s.
CBS News asked them how much Romney did pay in taxes the past 10 years, but they still wouldn't say.
All they'll say is that he paid all the taxes he was legally required to.
To see Nancy Cordes' report, click on the video in the player above.