Rising income inequality has been linked to political polarization. Krugman wrote in 2014, "The basic story of political polarization over the past few decades is that, as a wealthy minority has pulled away economically from the rest of the country, it has pulled one major party along with it ... Any policy that benefits lower- and middle-income Americans at the expense of the elite – like health reform, which guarantees insurance to all and pays for that guarantee in part with taxes on higher incomes – will face bitter Republican opposition." He used environmental protection as another example, which became a partisan issue only after the 1990s.