barack-obama_1_web.jpgTALLAHASSEE, Fla. (AP) _ Republican presidential hopeful Mitt Romney's pick of U.S. Rep. Paul Ryan as a running mate helped him slightly with some likely voters in three critical swing states although not enough to overtake President Barack Obama, who hung onto a slight advantage in Ryan's home state of Wisconsin, according to a poll released Thursday.

Obama led slightly in all three of the battleground states: 49 percent to 46 percent in Florida, 49 percent to 47 percent in Wisconsin and 50 percent to 44 percent in Ohio, which was unchanged from three weeks ago. The random telephone survey was conducted Aug. 15-21 by Quinnipiac (Conn.) University, CBS News and the New York Times. The margin of error in new poll was plus or minus 2.8 percentage points in each of its three separate surveys.

In earlier Quinnipiac polling results released on Aug. 1, Obama led Romney 51-45 in both Florida and Wisconsin.

Obama had a 51 percent favorability rating with voters in Ohio and Wisconsin and 50 percent in Florida compared to Romney, who is upside down with voters in Ohio, where 45 percent view him unfavorably compared to 39 percent who rated him as favorable. Romney was rated favorably by 45 percent of Florida respondents compared to 42 percent unfavorably and basically split with Wisconsin voters by a 44-43 margin.

Ryan, however, was seen more favorably than Vice President Joe Biden, although the Wisconsin congressman was seen as more qualified to become president only with the voters in his home state.

Voters in all three states rated Romney as the stronger candidate for handling the economy while they said Obama would do a better job on Medicare.

Medicare and the economy were each rated “extremely important'' by voters in the three states, which all went for Obama in his 2008 victory over Republican nominee John McCain.

“By more than a 4-1 margin, voters in each state say the health care program for the elderly is worth the cost and six in 10 say they favor keeping the current Medicare model,'' pollster Peter Brown said, adding that 10 percent said they would support major reductions in Medicare to reduce the deficit and nearly 50 percent would go along with minor reductions.

“Obama is the clear favorite in handling health care and Medicare,'' Brown said.

Poll-takers interviewed 1,241 likely voters in Florida, 1,253 in Ohio and 1,190 in Wisconsin via land lines and cell phones.