So when is news that appears to be good for a party not really something it should cheer about? This week may have been just such a time, after the Gallup Poll released a national survey showing Democrats with a 3-point advantage, 47 percent to 44 percent, on the generic congressional ballot test.

The results of the March 1-7 poll of 1,585 registered voters sound good for Democrats, who have had a lot of bad news over the past eight months or so, but were they? Two things make them less encouraging than they appear to be at first blush.

No. 1, Democrats hold 59 percent of House seats compared with the Republicans' 41 percent, which gives Democrats an 18-point spread. Democrats won 56 percent of votes cast for major-party House candidates in 2008, compared with 44 percent for Republicans -- a 12-point spread. Obviously, the 3-point edge on the generic is a lot narrower than the House Democrats' 18-point advantage in seats and their 12-point edge in the 2008 popular vote. (In 2006, when Democrats took control of the House, they won the major-party popular vote by 8 points -- 54 percent to 46 percent -- and simultaneously won an 8-point advantage in seats, 54 percent to 46 percent.)

Over the past 10 elections, the percentage of the major-party popular vote won by a given party's House candidates has averaged within 2.5 points of the percentage of seats won by that party. So for a Democratic Party heading into a midterm election in which it will have to try to defend an 18-point advantage on seats, poll results showing it a mere 3 points ahead on the generic ballot test are ominous indeed.

The second problem for Democrats searching for good news is that at this stage the Gallup Organization, which I admire enormously and which delighted me when it began releasing weekly generic ballot test results last week, is now surveying all registered voters, rather than just likely ones. Gallup does not believe in trying to weed out unlikely voters until much closer to the election -- September and October.

But as Gallup Poll Editor Frank Newport pointed out in releasing the results on Tuesday, "Republicans generally are more likely to vote in midterm elections than are Democrats, usually giving the former an advantage among likely voters." Over the years, Gallup has found that when it converts from registered to likely voters, support for Democrats usually drops about 4 points.

Also working in the GOP's favor this year is an enthusiasm gap. Gallup found that Republicans and Republican-leaning independents are 18 percentage points more likely than Democrats and Democratic-leaning independents to describe themselves as "very enthusiastic" about voting this November. What's more, young adults were an important part of the voting bloc that enabled House Democrats to expand their majority in 2008, but only 20 percent of voters who are 18 to 29 years old say they are very enthusiastic about voting this year. By contrast, 31 percent of those who are 30 to 49 are very enthusiastic, as are 39 percent of those 50 to 64, and 35 percent of those 65 or older. The average age of midterm voters tends to be far older than of those who cast ballots in presidential years. And the influx of new, young voters in 2008 may make the disparity even wider than usual.

Another poll released this week -- which veteran Democratic pollster Stan Greenberg conducted February 20-24 for the Democracy Corps and Third Way, a moderate Democratic think tank -- showed Democrats up by a similar margin, 2 points, 46 percent to 44 percent, on the generic congressional ballot. But Greenberg did try to screen the poll of 1,001 registered voters down to the 851 people likely to cast ballots this year. Doing that yielded a 3-point GOP advantage, 47 percent to 44 percent; the 150 voters unlikely to participate this year preferred Democrats by a whopping 25-point margin, 55 percent to 30 percent. Greenberg deemed 85 percent of the people in his overall sample "likely voters." My guess is that he included a lot of folks who are fairly unlikely to vote. Voter turnout for midterm elections tends to be only about two-thirds as high as turnout for presidential ones.

In short, the results of the latest Gallup and Greenberg polls, both expertly conducted, are not nearly as favorable for Democrats as superficial glances would suggest. Indeed, they portend a very challenging election for the party.

This article appeared in the Saturday, March 13, 2010 edition of National Journal.

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