Could the Democrats Win a Supermajority?

Whatever the outcome of the presidential campaign, Republicans may be in for a long night on November 4. The Democrats are poised to win so many seats in Congress that Republicans are warning about one-party rule if Barack Obama takes over the White House. The Wall Street Journal has editorialized about a "profound political and ideological shift" to "unchecked left-wing ascendancy." We look at the prospects for Democratic dominance. Can they win enough seats to overcome Republican filibusters in the Senate? What kind of majority can they get in the House? What about business as usual on Capitol Hill? Do special interests and public opinion moderate the potential excesses of either political party?