By STEVEN R. HURST
WASHINGTON (AP) _ President Barack Obama's re-election machine is trying to ruin any political honeymoon Republican challenger Mitt Romney sought to engineer by naming Rep. Paul Ryan as his running mate.
The president and Vice President Joe Biden were criticizing Romney as a supporter of the newly chosen Ryan's budget plans that would overhaul the Medicare health insurance program for the elderly and cut trillions of dollars from other social programs.
The debate was taking place across five battleground states Tuesday as both campaigns were at full speed heading into their politically important nominating conventions with less than three months before the election.
The tight race is dominated by a weak economic recovery and a national jobless rate of 8.3 percent. Polls taken before Romney added Ryan to his ticket over the weekend showed Obama with a slender lead in a contest that will be decided in eight to 10 battleground states.
Romney was in eastern Ohio coal country on the final day of a bus tour. Ryan was in Colorado and Nevada after being heckled by a handful of people on his first solo campaign outing Monday in Iowa.
Obama was also in Iowa for the second of three days there, while Biden, who opened a strong attack on the Republican ticket a day earlier, was campaigning in rural Virginia.
Biden continued the offensive Tuesday, telling supporters that Romney and Ryan are ''good men but they have fundamentally flawed judgment.''
''They call their plan bold and gutsy,'' Biden said of the budget plan that Ryan wrote and that Romney has generally endorsed. ''It's bold. But I don't get what's gutsy about giving millionaires another tax break. I don't get what's gutsy about gutting Medicare and education to pay for those things.''
All four candidates are in so-called swing states, which do not reliably vote for one party or the other in presidential elections. The presidency is not decided in the national popular vote but in state-by-state contests.
Romney has fought off attacks on Ryan's budget plans.
Ryan has ''come up with ideas that are very different than the president's,'' Romney said Monday in Florida, the state with the highest percentage of residents age 65 and over. ''The president's idea for Medicare was to cut it by $700 billion. That's not the right answer. We want to make sure that we preserve and protect Medicare.''
Romney did not say so, but the plans Ryan produced in the past two years as chairman of the House Budget Committee retain the $700 billion in Medicare cuts. Romney said there may be differences between his own budget plan and Ryan's, but he refused to get into details. Romney's staff said the former Massachusetts governor favored a plan to restore the $700 billion.
Romney on Tuesday tried to change the subject, addressing what he called the Obama administration's ''war on coal.''
''We have 250 years of coal. Why in the world wouldn't we use it?'' Romney asked, standing in front of workers at a coal mine in Ohio. He promised he would make the United States energy independent by the end of a second Romney term.
Obama, meanwhile, called on Congress to extend expiring tax credits for wind energy production. The White House on Tuesday pointed to a new Energy Department report saying wind power installations ''surged'' in 2011 but warning that uncertainty over extending the wind energy tax credits threatens to ''dramatically slow'' the industry.
''The wind industry now supports about 7,000 jobs in this state, and 75,000 jobs across the country,'' Obama said. ''These jobs aren't a fad - they're good jobs and sources of pride we need to fight for.''
Obama also mocked Romney for having once said, ''You can't drive a car with a windmill on it,'' declaring that his opponent was short-sighted on the need to find alternative sources of energy.
Romney has opposed extending the alternative energy credits, but several powerful Iowa Republicans, including the governor and a senator, favor the credits. That may give Obama the chance to create a local wedge issue to appeal to unaligned voters.
Associated Press writers Kasie Hunt, Matthew Daly and Ken Thomas contributed.