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Above: Rep. Paul Ryan, R-Wis., points to piles of the health care overhaul legislation during a markup hearing before the U.S. House Budget Committee last year in Washington, D.C.

The addition of Rep. Paul Ryan to the GOP ticket is certain to elevate health care as a campaign issue this fall. Most of the debate is likely to be about Medicare, and Ryan's controversial plan to transform the popular program for the elderly and disabled.

But some of the attention is likely to focus on Medicaid, the health care program for those with low incomes, as well.

Medicaid not Medicare is actually the nation's largest health insurance program, covering some 60 million Americans with very limited incomes. But you'd be excused for not knowing that, because Medicaid doesn't get nearly as much attention as Medicare does.

That may be changing, however. The Supreme Court earlier this summer put the program in the news when it ruled that the Medicaid expansion in the 2010 health law must be optional for states.

That's given more ammunition to Republicans, including presidential candidate Mitt Romney, who want to offer states far more responsibility for Medicaid.

"The state is the best place to determine what is the best way to help those poor," Romney said in a health care speech at the University of Michigan in 2011. "And so I would therefore block grant to the states' Medicaid funds, and say to the states, 'You now use these monies as you feel appropriate to care for your own poor.' "

Only there's a catch, said President Obama in a speech to Associated Press editors in April. Under the Republican congressional budget Romney has endorsed, Medicaid funding would not only be turned back to the states, it would be cut substantially.

"They would have to be running these programs in the face of the largest cut to Medicaid that has ever been proposed," he said, "a cut that, according to one nonpartisan group, would take away health care from about 19 million Americans."

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Medicaid Fight Enlivened With Romney-Ryan Ticket