Just when partisan Democrats were finally allowing themselves to revel in the expectation that they would sweep the House and maybe win the six seats needed for control of the Senate, two national polls released Sunday seemed to sound the first ominous notes from the theme music from “Jaws.”

Both polls showed the gap between Democrats and Republicans dramatically narrowing when likely voters were asked which party they intended to support for Congress. The Washington Post-ABC News poll had te Democrats leading by a 51-to-45-percent margin on the generic ballot question. A new survey by the Pew Research Center for the People & the Press had the Democrats ahead among likely voters by 47 to 43 percent. Two weeks ago the margin was 50 to 39 percent. And both surveys put George W. Bush’s approval rating above 40 percent, a rare high-water mark for the beleaguered president.

I don’t know how much confidence to put in the polls — not much is my guess — but to the extent that they’ve been wrong in the last couple of elections, they’ve been wrong in a way that understates, rather than overstates, the Republicans’ chances.

Meanwhile, this poll from USA Today shows Ford 46, Corker 49, which is pretty much a dead heat.

Shapiro concludes: “The truth is that — with unreliable or nonexistent polling in most House districts — virtually everyone in politics is flying blind as we enter into the desperate hours before Election Day.” And he also adds: “Democratic activists may not be able to emotionally survive another election night like 2004, which for many began with gleeful expectation that John Kerry would be president and ended with desperate plans to enter an ashram in Nepal. The level of despair if the Republicans manage to hang onto both houses of Congress could only be described by a Sophocles or an Aeschylus.” That probably won’t happen, but who knows?

Well, that’s why we have elections — to find out what voters want, not to ratify the guesses of pollsters.

UPDATE: For what it’s worth, I’m told that the Ford/Corker internals show a much closer race than the public polls, which is certainly how it seems to me.