ON NOVEMBER 9, less than 48 hours after Democrats captured the House and a few hours before Sen. George Allen conceded defeat to James Webb, giving Democrats control of the Senate, President Bush had lunch at the White House with Democratic representatives Nancy Pelosi and Steny Hoyer. In the brief photo opportunity following their meal, Bush played the gracious host. He twice thanked Pelosi and Hoyer for making the trip down Pennsylvania Avenue. He twice said the lunchtime conversation had been "constructive." And he twice congratulated Pelosi on her anticipated elevation to speaker of the House.

Pelosi, beaming, said she had offered Bush "the hand of friendship" and that the meeting had been "productive." She said she would work with the White House "in a confidence-building way" that "gets results." The two parties would debate the issues, she went on, but would also try to solve problems in a bipartisan manner. "We've made history," Pelosi said. "Now we have to make progress."

It was a fine sentiment, consonant with the view that last week's Democratic victory was essentially a rejection of the status quo in Washington and the conduct of American policy in Iraq. The electorate had voted to upend the balance of power and force change upon the capital. Whether the Democratic Congress will be able to bring change in a way that also broadens the party's appeal and bolsters its recent gains, no one knows. What seems plain, though, is that the greatest obstacle to future Democratic success is the Democrats

Over the next two years, there will be two Democratic parties. The congressional Democratic party will investigate the Bush administration and pass as much center-left legislation as possible. The presidential Democratic party, meanwhile-comprising aspirants to the executive office, senators Hillary Clinton, Joe Biden, Russ Feingold, and Barack Obama; former senator John Edwards; governors Bill Richardson and Tom Vilsack; perhaps Al Gore-will travel the country, raising money, holding debates, and laying the groundwork for a national campaign that might put one of them in the White House and (they hope) result in an era of unified Democratic control of government.

The great fear of some Democratic strategists is that the congressional party will behave in ways that alienate the independents who brought it to power, thus threatening the presidential party's chances for victory in 2008. "Will the presidential candidates in 2008 have to run away from the Democratic Congress, or will they be able to work together?" one think tank scholar asked last week. He thought the former more likely. And the congressional party's power structure and the nature of the incoming Democratic majority lend some support to his claim.

The Democratic congressional leadership is untested. With the sole exception of Harry Reid in the Senate, who was briefly majority whip during the 18 months of Democratic control between 2001 and 2002, none of the new leaders has ever served in the majority leadership. Pelosi, who was first elected in a special election in 1987, spent only seven years in Congress before the Republican Revolution of 1994. She became minority whip in 2001, when David Bonior resigned from the House to run for governor of Michigan; she became minority leader in 2002, when Dick Gephardt resigned from the House to run for president. In both leadership elections, Pelosi's chief rival was Steny Hoyer, a 12-term congressman from Maryland who is slightly to her right. When Pelosi became leader, Hoyer became whip.