MANALAPAN, Fla. — President Barack Obama is warning Florida retirees that Republican challenger Mitt Romney would undercut the new health care law and alter Medicare, a play for voters in one of the nation's top swing states.

Obama wraps up a two-day trip to Florida on Friday with stops in Fort Myers and suburban Orlando, where he is pressing the case that retirees would be hurt by Romney's opposition to the health care law and by Republican-led efforts to turn Medicare into a "voucher program." Romney is keeping his focus on the economy, charging that Obama remains more concerned about holding onto his own job than creating more jobs for Americans.

In pre-convention summertime campaigning, Obama and Romney are locked in a tight contest and seeking advantages in about a dozen toss-up states that could help decide the election. None is more prominent than Florida, which narrowly decided the 2000 election and could provide a major boost to whoever prevails here.