Sorry Democrats, 2018 won't be the blue wave you were hoping for All Democrats have to do in order to retake Congress in November is avoid appearing to be smug, paternalistic scolds. No can do.

Christian Schneider | Opinion columnist

In 2004, Democrats had a momentum no amount of Super PAC money could buy. After President George W. Bush’s approval rating soared to 90% following the 9/11 attacks, he steadily lost ground, sinking to his pre-election approval level by early 2003. After Bush ordered the invasion of Iraq in March of that year, his numbers once again spiked to nearly 75%; yet after American fatalities mounted and no evidence of weapons of mass destruction was found, Bush plummeted to the mid-40% mark by early 2004.

With a public disaffected over the prosecution of the war, it appeared Republicans faced long odds to hold the presidency. But to loosely paraphrase Die Hard’s Hans Gruber, “You ask for a miracle, I give you … John Kerry.”

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Over the summer, Democratic Sen. John Kerry of Massachusetts held a consistent polling lead over Bush, but that lead evaporated as the calendar turned to September. Kerry failed to properly respond to the famous “Swift Boat” advertisement that painted him as a Vietnam War opportunist, and his attempt to have it both ways on the Iraq war exposed him as an inveterate flip-flopper. Week after week, Saturday Night Live savaged Kerry for changing his position on the war depending on which type of audience he was addressing, with Seth Meyers’ Kerry character excusing his behavior by explaining he wasn’t “flip-flopping,” he was simply “pandering.” (Spoiler alert: Bush won.)

In the 2018 midterm elections, Democrats once again are buoyed by low Republican approval ratings. According to FiveThirtyEight.com, President Trump’s approval currently sits at 42.2%, up from his low of 36.6% in August of last year, and slightly below Bush’s approval in May of 2004.

But in the past six months, the generic congressional ballot has been cut in half, from a Democrat lead of roughly 13% in December to about 6% now. While still behind, Republicans are closing the gap, suggesting 2018 may not be the “blue wave” many expect.

The idea of the GOP retaining both houses of Congress seemed fantastical just months ago. But polling “gaps” have two components; a voting gap can shrink either if the losing party picks up more popular support or if the party in the lead begins to lose ground. Since the beginning of 2018, Republicans have picked up around three percentage points, but Democrats have also plummeted five points.

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The lesson, as Americans saw in 2004 and even more spectacularly in 2016, is that there is no lead too large for Democrats to blow.

For one, individual races are run by individual candidates, and regardless of what the national mood might be, people vote for House or Senate hopefuls based on the candidates’ personalities. Even though a majority of Americans personally disliked Donald Trump in 2016, enough people in battleground states loathed Hillary Clinton even more.

Two years later, Clinton’s off-putting brand of condescension is making a spectacular comeback. Just in the past week, liberal billionaire megadonor Tom Steyer suggested Trump should be impeached before the U.S. president becomes another Adolf Hitler. Former Democratic National Committee chairwoman Debbie Wasserman-Schultz told Huffpost that the National Rifle Association is “just shy of a terrorist organization.” America recently watched in horror as a Utah teenager was stoned in the progressive public square for daring to wear a Chinese-themed prom dress.

In a year so favorable, it would appear all Democrats have to do in order to retake Congress is avoid appearing to be smug, paternalistic scolds. And yet the party’s temptation to self-immolate is once again proving too strong. It as if Democrats have begun dousing one another with anti-voter repellent.

While liberals do have a number of special election victories to brag about over the past year, the zeitgeist appears to be shifting. The economy is roaring, with unemployment plummeting and the stock market surging — both points you’re likely to hear from Republicans until your ears bleed. Further, November is a long way off; no one can predict what issues will overtake the American conscience before voters begin heading to the polls, and in many cases, we don’t yet know who the candidates will even be.

So even though parties in power tend to lose seats in midterm election years, Democrats may not succeed in convincing Americans that Ragnarok is upon us. Over the next few months, liberals are going to argue the country is worse off because Republicans have changed; yet the real problem might be that Democrats haven’t.

Christian Schneider is a member of USA TODAY's Board of Contributors. Follow him on Twitter: @Schneider_CM.