The Post is taking a comprehensive look at the positions of President Obama and Mitt Romney on several key issues. After the economy, no subject stirs passions among voters more than health care. President Obama and Mitt Romney have been arguing about it throughout the campaign. Two issues are now front and center. The first is the president's health-care law, passed against Republican opposition in 2010. The law has come to symbolize all that conservative Republicans believe is wrong with Obama's presidency, including the cost of the legislation and the government's role in the health-care market. The measure stirs passions among Republicans who hate it; Democrats who like it feel far less passionate about it. The newer issue in the debate between Obama and Romney is one that has been used in campaigns for decades: Medicare.