Updated

The U.S. presidential campaigns were trying to win older voters Friday, with a new video by President Obama's campaign arguing that Republican rival Mitt Romney derides seniors behind closed doors.

The race for the November election remains tight, though Obama holds a slight lead in recent polls and has pulled ahead in cash on hand for the crucial final campaign push.

Romney's running mate, Paul Ryan, brought along his 78-year-old mother for an appearance before the national convention of the AARP, a nonpartisan group that claims to have 37 million members age 50 and above. Ryan told attendees that he and Romney care about senior citizens.

"Mitt Romney and I share your concerns," Ryan said in remarks provided by the campaign in advance. "And we respect you enough to level with you."

Ryan argued that Obama's widespread health care overhaul has weakened Medicare, the popular federal entitlement program for seniors, and said Romney would give seniors more choice in their health care coverage if elected.

Americans 50 and over are especially important for the candidates because they register in greater numbers and are almost twice as likely to cast their ballot as younger voters. An Associated Press-GfK poll released this week found Romney was favored by seniors likely to vote, 52 percent to 41 percent for Obama.

Obama also appeared before the AARP convention live via satellite from Virginia, where he was holding a rally Friday. He told the audience that entitlement programs like Medicare and Social Security "are not handouts. You paid into these programs your whole life. You earned them."

His campaign also launched an ad Friday in the key battleground states of Colorado, Florida and Iowa that argued Romney and Ryan would turn Medicare into a voucher program that could raise seniors' health costs by up to $6,400 a year.

Ryan said his plan would create competition among private insurance providers and bring down costs.

Obama's campaign also released an online video that argued "Romney thinks more than half of senior citizens `don't `care for their lives."' It includes remarks that Romney made to donors while being secretly recorded in May, in which he said nearly half of voters support Obama, don't pay income taxes and are dependent on government. "My job is not to worry about those people. I'll never convince them they should take personal responsibility and care for their lives," Romney said in the video, released this week on the website of Mother Jones magazine.

About 22 percent of those not paying income tax are seniors who get tax breaks that offset their income.

Polling shows Obama with a slight lead nationally, as well as in many of the eight or so battleground states that will decide the election. The president is not elected by popular national vote but in state-by-state contests.

Obama has also pulled ahead of Romney in cash on hand, a key measure of a campaign's financial strength. Obama has more than $88 million to spend in the campaign's final weeks, while Romney has just over $50 million.

Romney is facing criticism from some in his own party that he's spending too much time raising money and not enough time talking to voters in the states that will decide the election. In response, his campaign added a Sunday rally in Colorado to his schedule and announced a three-day Ohio bus tour that begins Monday.

At the same time, his wife, Ann, said Republican critics should lay off. "Stop it. This is hard. You want to try it? Get in the ring," she said Thursday evening in an interview with Radio Iowa.