The polls keep getting worse for the Democrats. Last week, Gallup showed the Republicans ahead by ten points — 51 percent to 41 percent — on the question of who registered voters would prefer to elect to Congress. This is the biggest generic ballot lead for the GOP in sixty years of polling by this venerable organization.

On most issues, voters preferred congressional Republicans to their Democratic counterparts. The only issue on which Democrats retained a statistically significant advantage was the environment. Compared to where they were in the last election, the Washington Examiner‘s Byron York noted, there has been “a 38-point swing on health care, a 27-point swing on the economy, a 26-point swing on handling corruption in government, a 29-point swing on combating terrorism” — all away from the Democrats and toward the Republicans.

Then came a Washington Post/ABC News poll that showed Republicans with a 13-point lead in the generic ballot. Fully 92 percent of Americans said they believed the economy was in bad shape, with more disapproving of President Obama’s handling of that issue than approving. Dissatisfaction with the workings of the federal government was at it highest level since the month before Bill Clinton denied George H.W. Bush a second term in 1992.

The same day that poll was released, the Cook Political Report projected a Republican takeover of the House. Leading prognosticator Charlie Cook’s newsletter estimates that the GOP will gain at least the 40 seats it will need to regain the majority but the gains could be “very possibly substantially more.”

“Happy Days Are Here Again” is a New Deal-era tune Democrats long danced to. Should Republicans start singing it? The Washington consensus on the GOP’s 2010 electoral outlook ranges from moderate gains to huge gains, reminiscent of Stephen Colbert’s gag about George W. Bush: “Greatest president or great president?” As Sarah Palin quipped, “I can see November from my house.”

Number-cruncher Sean Trende of RealClearPolitics (yes, Trende is apparently his real last name) has been the most serious proponent of what we might call the maximalist case for the Republicans in this election. Way back in April, Trende wrote that “those who suggest that the House is barely in play, or that we are a long way from a 1994-style scenario are missing the mark. A 1994-style scenario is probably the most likely outcome at this point.”

Trende is now doubling down, predicting a “once-in-a-century storm” (the title of his latest piece is “Bigger Than 1994”). If the Republicans perform roughly as well in the national popular vote as they are faring in the generic ballot polls, he argues that the numbers predict substantial GOP gains. Even the one macro indicator that remains in the Democrats’ favor — the fact that Barack Obama still has a significantly higher approval rating than George W. Bush before the 2006 debacle — could be masking a problem.

Obama’s massive popularity with liberals, young people, and minorities might help his overall approval ratings, but this refurbished Dukakis coalition won’t be enough to keep Democratic congressional candidates from losing. These voters are mostly packed in already safe congressional districts and their turnout won’t approach 2008 levels without Obama himself on the ballot.

Now for the cold water: The micro indicators don’t look nearly as good. Republicans have lost most special elections since Obama became president. The party’s campaign committees are at a cash disadvantage against the Democrats and Michael Steele’s Republican National Committee bears a closer resemblance to the Titanic than to a well-run ship. Many Republican challengers in key districts are underfunded, a fair number of them are political neophytes, and there is little evidence of a sophisticated get-out-the vote operation.

The GOP’s biggest special election coup in the age of Obama was Scott Brown’s surprise election to the U.S. Senate from Massachusetts. There the national party had little to do with his rise (though their infusion of cash did help him over the finish line), Brown was a rare Republican who had won multiple prior elections in the deep blue Bay State, and his Democratic opponent Martha Coakley was a one-woman turnout dampening operation. Republicans won’t be so lucky across the country.

The common thread in special elections Democrats have won is that they have succeeded in putting distance between themselves and the national party brand while their Republican opponents have tried to nationalize the election. Brown, by contrast, was successful in combining national and local themes while Coakley often behaved as if she had been dropped into Massachusetts by a UFO from Mars.

But how successful can Democratic incumbents be at denationalizing their races if they have a proven track record of voting in lockstep with the national party on controversial issues? The conditions do seem right for Republicans to retake Congress, with the major caveat of whether Republicans are prepared to take advantage of these conditions.

While writing a magazine article before the 2006 midterm elections, I asked a nationally known Democratic consultant if he thought this would be his party’s equivalent of 1994. He told me that 1994s don’t come along very often, so he was hesitant to predict one. Given how that November turned out, he was probably being too cautious. Are those predicting a narrowly Republican House being too cautious this year?