The latest poll gives Obama an almost identical lead — 13 points — among likely voters. Earlier versions of the poll only included registered voters.
Obama's campaign has made Medicare a centerpiece of its attacks against Romney and Rep. Paul Ryan (R-Wis.), saying their plan to partially privatize the program would require seniors to pay thousands of dollars more to keep their benefits, and could spell the end of the program altogether.
The Post/ABC poll is the exact opposite of a survey last week from the Pew Research Center, which showed Obama's lead on Medicare shrinking from 13 points to just 3.
The Pew survey was conducted in the days immediately following Obama's poor performance in the first presidential debate, while the Post/ABC survey followed the stronger performance by Vice President Biden, who framed Medicare as an issue of trust in his debate with Ryan.
But Obama has not managed to pull away on healthcare overall, according to the Post/ABC poll. He holds just a 1-point lead (47-46 percent) among likely voters, and a 6-point lead (49-43 percent) among registered voters. Since July, Obama has led Romney by 2 to 4 points on healthcare in the Post poll.
Other surveys have given Obama a wider lead on healthcare, though last week's Pew poll showed his lead shrinking dramatically on healthcare as well as Medicare.