If you're a Democrat, E. J. Dionne's column is depressing.

But the party's problems are structural and can be explained by three numbers: 21, 34 and 45. According to the network exit polls, 21 percent of the voters who cast ballots in 2004 called themselves liberal, 34 percent said they were conservative and 45 percent called themselves moderate.

Those numbers mean that liberal-leaning Democrats are far more dependent than conservatively inclined Republicans on alliances with the political center. Democrats second-guess themselves because they have to.

Consider that in 2004 Democrat John Kerry won 85 percent of the liberal vote and defeated Bush by a healthy 54 percent to 45 percent among moderates. But Bush prevailed because he won 84 percent of a conservative vote that constitutes more than a third of the electorate.

Or consider the lay of the land for the 2006 congressional elections. It takes 218 seats to form a majority in the House of Representatives. Kerry carried only 180 congressional districts, according to the Almanac of American Politics. Put another way, Democrats, according to the Almanac, now hold and have to defend 41 House districts that Bush carried. Republicans are defending only 18 districts that Kerry carried.

The core difficulty for Democrats is that they must solve two problems simultaneously -- and solving one problem can get in the way of solving the other. Over time Democrats need to reduce the conservative advantage over liberals in the electorate, which means the party needs to take clear stands that could detach voters from their allegiance to conservatism. For some in the party this means becoming more moderate on cultural issues such as abortion. For others it means full-throated populism to attract lower-income social conservatives. Some favor a combination of the two, while still others worry that too much populism would drive away moderate voters in the upper middle class. The debate often leads to intellectual gridlock.

Their main message is that Bush and the Republican stink. People may even agree with them, but that is unlikely to motivate enough people to come out and vote the Democrats into control of either the House or the Senate. The numbers are against them. The GOP have a structural advantage simply by having painted 31 of 50 states red last year. Admittedly, some states were close, but so were some of the blue states. The Democrats need a positive message that attracts more than the Bush-haters. They need a message that will peel away the moderate voters but still attract those on the extreme left. That may be a difficult coalition to pull together.

So, basically, both parties are in difficult spots. That is what makes politics so entertaining to watch. Governing -- that's just not as fun to watch.