DELRAY BEACH, Fla. -- Heading into the campaign's final weeks, Republican presidential candidate Mitt Romney is upping his criticism of President Barack Obama's plans for a second term, accusing the Democrat of failing to tell Americans what he would do with four more years.

The president's aides are particularly irked by the questions about Obama's second-term agenda. They say it is Romney who has failed to provide voters with details. They point to his refusal to provide specifics about his tax plan or outline what he would replace the president's health care overhaul with if he makes good on his promise to repeal the federal law.

At campaign events, in a new ad and fundraising appeal out Saturday, Romney is setting up the closing weeks as a choice between what he says is a "small" campaign offering little in the way of new policies and his own ambitious plan to fundamentally change America's tax code and entitlement programs.

The Romney ad criticizes the president's policies on debt, health care, taxes, energy and Medicare, arguing that Obama simply is offering more of the same. The fundraising appeal hits Obama for raising taxes and increasing the debt by $5.5 trillion, repeating the lack-of-agenda criticism.

"Although President Obama won't lay out his plan for a second term, we already know what it will be -- a repeat of the last four years. We can't afford four more years of crushing debt and wasteful spending," Romney says in the letter, adding he has a clear plan to put America on a path to prosperity.

Obama and Romney retreated from the campaign trail Saturday to bone up on foreign policy, leaving the work of courting voters to their running mates.

Romney's running mate, Paul Ryan, on Saturday continued the no-agenda theme against Obama at campaign stops near Pittsburgh and in Belmont, Ohio.

"He's not even telling you what he plans on doing," Ryan told a rain-soaked crowd of about 1,100 people in coal-rich eastern Ohio.

Obama's campaign disputes the notion that the president hasn't outlined a detailed second-term agenda, pointing to his calls for immigration reform, ending tax breaks for upper income earners, fully implementing his health care overhaul and ending the war in Afghanistan.

Campaign spokesman Danny Kanner ticked through a series of policy items, calling them "just part of President Obama's agenda for a second term."

Obama, at the Democratic National Convention, called for creating one million manufacturing jobs during the next four years with a mix of corporate tax-rate cuts and innovation and training programs.

He has set a goal of cutting the growth of college tuition in half over the next 10 years. He also has called for Congress to pass proposals he made last year that include tax credits for companies that hire new workers and funding for local municipalities to hire more teachers, police officers and firefighters.

As for why Republicans would back the same proposals they have already voted against, Obama has told supporters he expects his re-election would "break the fever" on Capitol Hill that led to gridlock during his first term.

Vice President Joe Biden made a diagnosis of his own Saturday, saying Ryan had caught "Romnesia," the word Obama used the day before to describe what he calls Romney's changing polices.

"That man is contagious," Biden said of Romney, to loud cheers at a campaign stop in St. Augustine, Fla. "Congressman Ryan caught it as well."

He said the Wisconsin congressman is giving a new explanation for cuts in the budget he oversaw and passed in the House.

Monday's third and final presidential debate will be in Boca Raton, Fla., with its focus on international affairs. It comes just 15 days before the election.

Obama left Friday for Camp David, the presidential hideaway in Maryland's Catoctin Mountains, where he is huddled with advisers preparing for the debate. Among those with him are White House senior adviser David Plouffe and senior campaign strategist David Axelrod. Aides say Obama was also being assisted by National Security Adviser Tom Donilon and former Obama aide Karen Dunn.

Romney was also with aides preparing for the debate, spending the weekend in Florida.

Both campaigns are heavily targeting Florida and its 29 electoral votes -- the most of any tossup state. It was the second day of a two-day Florida swing for Biden, which overlapped a two-day swing by Ryan. Romney's wife, Ann, was also in Florida on Saturday and first lady Michelle Obama planned a visit Monday.