WASHINGTON — Get in line, Medicare and Social Security. Seniors, like just about everyone else, have money on their minds.

Who wins the trust of seniors, a group that votes at a higher rate than any other, will be a deciding factor in the presidential election. That should be good news for Mitt Romney, because those 65 and older have backed the Republican candidate in both of the last two presidential elections.

But President Barack Obama has been pounding Romney and his running mate, Rep. Paul Ryan, on their plan for Medicare. Those attacks are starting to bear fruit for Obama, who is gaining ground among seniors in two key battlegrounds: Florida and Ohio.

Still, Romney has the edge nationally among seniors — in no small part thanks to seniors’ concerns about Obama’s handling of the economy.

Nowhere will the senior vote be as powerful or as prominent as in Florida, where Romney and Obama are competing fiercely.

“It’s not just the cookie cutter that every senior here is totally dependent on Social Security and Medicare,” said Susan MacManus, a political scientist at the University of South Florida. “As the FDR generation has passed and generational replacement has occurred, you get a more divided senior electorate.”

More seniors say the economy is extremely important to their vote than Medicare, says a poll released Thursday by the nonpartisan Kaiser Family Foundation. A recent Associated Press-GfK poll shows 7 in 10 seniors say taxes and the federal deficit are important to them.

Even for those well into retirement, a feeble economy affects older Americans in ways you might not realize. Many have had to bail out adult children who have lost their jobs and turned to their aging parents for help.

.And those who lived through the Great Depression as children relate intimately to the perils of an over-indebted nation.

Just ask Dominic Santoro, an 81-year-old retiree from Sunny Isles Beach, Fla., who said it’s different for seniors than it is for younger Americans, who have years to make up what was lost during the recession.

“That’s very nice, but what about the poor senior citizen that’s no longer working and can’t replace that money?” said Santoro, who plans to vote for Romney.

But if seniors’ concerns extend beyond entitlements, those seeking the White House don’t seem to have caught on.

Obama and Ryan both hewed closely to themes of Medicare and Social Security in their speeches last week to an AARP summit in New Orleans. Ryan, who was loudly booed for vowing to repeal “Obamacare,” offered assurances that he and Romney wouldn’t alter Medicare for those in or near retirement.

“Medicare is a promise, and we will honor it,” Ryan said. “A Romney-Ryan administration will protect and strengthen Medicare — for my mom’s generation and for my kids and yours.”

Not so, said Obama, warning seniors that Ryan and Romney want to replace Medicare with vouchers that wouldn’t keep up with health care costs. It’s an admonition echoed in a television ad Obama’s campaign started airing Friday in Florida, Colorado and Iowa.

Both Ryan and Romney invoked their late grandmothers in working to convince AARP members that they understand what seniors go through.

“She was a great citizen who lived up to her responsibilities,” Obama said. “And after a lifetime of hard work, what she hoped for in return was to be able to live out her golden years with dignity and security, and to see her grandchildren and her great grandchildren have a better life.”

Although far from a monolithic bloc, seniors by and large have sided with Romney throughout this year’s election and favored the former Massachusetts governor 52-41 in a national AP-GfK poll in September. While Romney has lost his edge among overall voters on handling of the economy, seniors are the holdout, preferring Romney by 10 points over Obama on that issue.

But in competitive states that could determine the election’s outcome, seniors’ attitudes are on the move. Over the past month, Obama has climbed 9 points in Florida and 4 points in Ohio, giving him an edge over Romney in both states, according to a new Quinnipiac University/CBS News/New York Times poll. It’s the opposite in Pennsylvania, where Obama has lost his edge among seniors and now trails Romney 45-50.

Older voters will make up a dramatically larger part of the population in the coming decades, according to a report released Tuesday by the National Academy of Sciences. Americans are living longer, working longer and waiting until later in life to have children.

In the near term, that shift may work in Republicans’ favor, offsetting some of the boost that Democrats are expected to enjoy from the growing minority population.

Those who witnessed a post-Depression resurgence tend to fondly recall FDR’s New Deal and may be more likely to vote Democratic, said William Frey, a demographer at the Brookings Institution, a Washington think tank. But as time marches on, they’ll be replaced by their younger counterparts.

“The ones who came up since then, the so-called ‘Silent Generation, has moved more conservative on fiscal issues,” said Frey. They came into their own in the 1950s and 1960s, saved their money and want to know those savings will still be there when it’s time to draw them out.

Their children, the baby boomers, are more fragmented when it comes to their financial situations and living arrangements. Many had fewer children than their parents’ generation and now, facing retirement, have less support from their sons and daughters. Some have solid pensions and are in good shape. Still others are female heads of household with little savings.

And for many of those who grew up in an America marked by the turbulence of World War II, global unrest and anti-American rage may be all the more disconcerting.

“I used to be proud to be an American,” said Diane Fritz, a 69-year-old Romney supporter from Port Charlotte, Fla. “We don’t even look like we’re a strong country anymore.”

Barbara Kelleher, 66, an Obama supporter, put it another way:

“Suddenly you think, ‘What’s going to happen and how is this going to affect my grandchildren’s future?”’ said Kelleher, of Loveland, Colo. “You want the world to be a safe place.”