Donald Trump's seeming invulnerability to the laws of politics, chameleon self-presentation, and left-leaning views on social insurance and trade led me to think that he might be a serious contender for the general election. I'm beginning to believe the opposite. While any major party nominee surely has a shot, Trump is looking increasingly unlikely to shed his deranged primary image.

His campaign manager has been charged with battery, and the case against him is pretty strong (including damning video evidence). Trump, naturally, denies the whole thing. His rallies continue to be a swirl of violence and racism. Naturally, he topped off a week of terrible press by suggesting that there should be "some form of punishment" if women have illegal abortions, then immediately walked it back. As a result, his popularity is approaching that of an epidemic disease. Women, minorities, and college grads all dislike him by monumental proportions, and as Greg Sargent points out, a recent poll finds that even an absolute majority of white men have an unfavorable opinion of Trump.

If recent history is any guide, all that won't be enough to derail the Trump Train. He remains at the top of the primary polls, and similar controversies have failed to stop him. His support from a plurality of the Republican electorate seems unshakable — but he might lose the general election by 15 points or more. This raises the question: Are Democrats about to bobble a spectacular stroke of good fortune?

Gerrymandering and Democratic voter concentration combine with America's antiquated constitutional structure to give Republicans a tremendous handicap in the House, something like 7 percentage points. Trump might deliver Democrats a greater margin of victory than that, but it will depend on the party actually contesting a whole bunch of elections nationwide. And as David Dayen points out, state-level Democrats are badly hurting from years of Republican dominance and terrible management by the Democratic leadership. In states whose filing deadlines have already passed, 27 out of 163 elections are not being contested by Democrats — about six of which might plausibly have been won in an anti-Trump landslide. Whoops!

Given the Republican hammerlock, Democrats would need everything to break their way to win control of the House. Those six seats might be the fumbled Democratic majority right there — and there are a whole bunch more filing deadlines coming up in the coming days and weeks.

The problem is undoubtedly worse at the state and local levels. Democrats have lost over 900 state legislative seats since 2009 — which partly explains why they're having such trouble rustling up national candidates, since local and state officials are usually the farm team for the political big leagues.

Due to this failure to maintain a consistent party apparatus even in close districts, some of the candidates who are contesting House races are relative political newcomers with serious misconceptions about their own political fortunes. Take Colorado's third congressional district, which was held by a Democrat from 2006-10 and just recently got a Democratic primary entrant named Steve Sheldon.

That's all good! Unfortunately Sheldon describes himself as a "centrist Democrat and fiscally conservative."

By far the biggest reason the Democrats got absolutely creamed in the 2010 election was that the economy was in the toilet, and perhaps the biggest reason it was in that toilet was precisely attitudes like this. Despite its many virtues, President Obama's economic stimulus failed to restore full employment by mid-2010, when Democrats still had their majority. But centrist Blue Dog Democrats in swing districts, instead of demanding more spending to fix the recession and create jobs before the election, demanded austerity instead. As a result, virtually all of them lost their seats in the 2010 GOP wave.

Now, things are much improved today, but there is still obviously at least some economic slack remaining. Therefore, one obvious top priority of any Democratic president with a workable congressional majority would be a big new spending program, perhaps on infrastructure, or perhaps on paid leave or some other social benefit, to create prosperity and thus protect the majority. Running against austerity paid dividends for the Liberal Party in Canada.

But because the Democratic Party has failed to understand its own self-interest, or consistently field candidates for winnable races, even if Trump hands them a congressional majority they might not be able to keep it.