The Washington Post/ABC poll supposedly serves as a dire warning to the GOP and to the Tea Party that they have already peaked.  It might be true, too, if Democrats work out a nine-point advantage in turnout in November.  That’s the partisan gap among registered voters in their sample, which to be fair, still improves on the ten-point advantage they gave Democrats in April.

Even with that, the poll warns Democrats more about the dangers of an anti-incumbent tide:

As voters head to the polls Tuesday for a crucial set of primary elections, a new Washington Post-ABC News poll finds antipathy toward their elected officials rising and anti-incumbent sentiment at an all-time high.

The national survey shows that 29 percent of Americans now say they are inclined to support their House representative in November, even lower than in 1994, when voters swept the Democrats out of power in the that chamber after 40 years in the majority.

The poll also finds growing disapproval of the “tea party” movement, with half the population now expressing an unfavorable impression of the loosely aligned protest campaign that has shaken up politics this year.

Now would be a good time to look at that sampling.  Despite numerous polls this year showing the partisan identification gap between Democrats and Republicans narrowing to its smallest number in at least five years, the Post’s sample shows 34% Democrats, 25% Republicans, and 38% independents among the registered voters in this survey of the general adult population.  To put that in perspective, Barack Obama won the presidential election in 2008 with a seven-point advantage in the national popular vote — in what was a big turnout year for Democrats.

In April, Gallup put the partisan gap down to a single point.  Take the eight point advantage away from Democrats, and that opinion of Tea Parties would undoubtedly shift back into positive territory.

That might also have some impact on Barack Obama’s approval rating, too.  They have it at 52/45, down from 54/44 two months ago.  That eight-point shift would more or less reverse Obama’s approval rating, putting him in roughly the same position as Gallup and Rasmussen, in the mid-40s or lower.  Even without the correction, Obama is seriously underwater on the federal deficit (39/56) and now on the oil spill (44/49).  Obama got his best rating in months on the economy, just as jobs have started to slide again, 50/49.

In leadership, Obama has taken some serious damage.  The numbers themselves look all right, with Obama getting a “strong leader” approval of 57/43 and “understands our problems” rating of 51/48.  However, both are significant drops from the March poll, which had him at 65/33 and 56/43, respectively, and both of those down from the January poll.

Democrats in Congress have big problems, too.  Given that eight-point head start, their 45/40 edge about which party has the right idea of the role and size of the federal government is small consolation.  Only 29% want to re-elect their incumbent Representative, down from 37% in February.  That’s a new low; even in 1994, that was 37% in the WaPo/ABC poll.  Given that there are a lot more Democrat incumbents, the indication is for a big turnover.