WASHINGTON – A little more than two weeks before Election Day, Republicans and Democrats alike say Medicare is working to their political advantage in campaigns for the White House and Congress.

They can’t both be right, and no matter which side is, this is one campaign clash with consequences extending well beyond Nov. 6.

Mitt Romney “would replace guaranteed benefits with a voucher system,” says a commercial that President Barack Obama’s campaign aired in several states this fall. “Seniors could pay $6,000 more a year. A plan AARP says would undermine Medicare,” it adds, making claims that Democrats in congressional campaigns echo in ads of their own from New York to California.