The parties clearly differ now on a number of important issues. The Democratic Party is more uniformly liberal today than it was a few decades ago, and the Republicans are more consistently conservative. The idea of responsible parties, also called party government, offers a vision of democracy very different from the traditional American commitment to limited government and the equally traditional American hostility to powerful political parties. Critics of party government also fear that a system that makes parties the main avenue of political representation could undercut the rich variety of interest groups that now exist. American voters have made enthusiastic use of the separation of powers in recent years. Americans got at least a whiff of party responsibility starting in the mid-1990s. Spearheaded by House Republican minority leader Newt Gingrich, the great majority of Republicans running for House seats in 1994 signed a statement called a "Contract with America".