When is a portent important?

That's the question the political world has wrestled with since Tuesday's Democratic electoral sweep, crowned by Ralph Northam's nine-point victory over Ed Gillespie in the Virginia governor's race and the party's down-ballot romp in the commonwealth.

Was this the natural buoyancy of an out-of-power party in a purple-turning-blue state or did the GOP drubbing there and elsewhere signal a deeper anti-Trump backlash that could build into a 2018 Democratic wave?

One way to answer that question is by fleshing out the political context in which Tuesday's races occurred, the identifiable national data points and campaign trends. Nothing in politics is guaranteed, ask Hillary Clinton (and her boosters), especially 12 months before the 2018 voting; but even aside from Tuesday's wins, circumstances are starting to align the way Democrats would need them to for a big year.

Start with the bottom line: Democratic House candidates are raising money, lots of it. Politico's Elena Schneider reported last month, when the latest batch of campaign finance reports were released, that at least 162 Democratic candidates in 82 Republican-held House districts had raised over $100,000. "That's about four times as many candidates as House Democrats at this point before the 2016 or 2014 elections and, and it's more than twice as many as Republicans had running at this point eight years ago, on the eve of capturing the House in the 2010 wave election," she wrote. And National Journal's Josh Kraushaar added that among the 53 House Republicans in races rated as competitive by The Cook Political Report, 21 had been outraised by at least one (and in some cases more than one) Democratic challenger. "That's a stunningly high number," Kraushaar noted, adding that the Democrats' money surge was leaving House Republicans "increasingly alarmed that some of their vulnerable members aren't doing the necessary legwork to protect themselves from an emerging Democratic tidal wave."

More broadly, the Democratic Congressional Campaign Committee outraised its GOP counterpart for the fifth month in a row in September, per Politico. This isn't to suggest that it's all bad news for the GOP: The Republican National Committee has raised over $100 million while the Democratic National Committee is facing severe financial problems. But it's clear that financially, Democrats are on the offense – and not surprisingly, given that poll numbers also broadly favor the party. There's President Donald Trump's dismal approval rating, which stood at 38.2 percent in the HuffPost Pollster average as of Thursday morning, with 56.9 percent disapproving. Dig deeper and it gets worse: More people strongly disapproved of Trump's job performance than approved at all in recent polls from The Economist/YouGov (43 strongly disapprove versus 37 percent net approve), Ipsos/Reuters (44-35), CNN (48-35) and Washington Post/ABC News (50-37). Again, that's not disapprove versus approve, that's strongly disapprove versus approve at all. That's what a political albatross looks like and you could see it Tuesday in Virginia, where exit polls showed that 57 percent of voters disapproved of the job Trump is doing as president and that 34 percent of voters cast their ballots to express opposition to him.

And while Trump's tenure on the national political stage has been marked by questions about the extent to which his negatives rub off on his party, national polls about who voters want running Congress, the so-called generic ballot, favor Democrats. The RealClearPolitics average of polls had Democrats ahead by 9.7 percentage points Thursday morning (HuffPo Pollster's average is closer with Democrats only enjoying a 4.4 percentage point margin). There is a vigorous debate about when we should start to look at the generic ballot as predictive, but it is illustrative as a snapshot of the current political environment. And now is the time when challengers are deciding whether to get into races and incumbents are pondering getting out of them.

And Republican lawmakers are starting to get out. Often overlooked amid the Virginia headlines Tuesday were the announcements that Republican Reps. Frank LoBiondo of New Jersey and Ted Poe of Texas would not seek re-election; they were joined Thursday by Virginia GOP Rep. Bob Goodlatte. Overall, 30 Republican House members over the past year have either quit or indicated that they won't run again. And as The Washington Post's James Hohmann has noted, that exodus contains a surprising number of committee chairmen; Goodlatte, for example, chairs the powerful Judiciary Committee.

The House GOP flight only figures to go up in the coming weeks and months. "We were already set to see a whole bunch of Republican retirements in the House," veteran political handicapper Charlie Cook said at a National Journal event on Wednesday morning, adding that the Virginia wave would only augment that trend. Not all retirements are created equal, mind you. Poe's seat should be safely Republican; but seats like LoBiondo's instantly become new top targets for Democrats. "To the extent that you have Republicans in competitive districts leaving ... and Democrats have any kind of tail-wind at all it puts the Republican majority in the House in jeopardy," Cook said.

That trend will only be spurred by Virginia's wipeout and the prospect of an uphill battle just to stay in office, let alone stay in a miserable and unproductive majority in Trump's Washington.

And who would want to, really? The promise of unified control of government bringing long sought-after policy changes has dissolved into floundering chaos.

Trump has, no surprise, failed to pivot to a presidential mien; one of his top lieutenants, Steve Bannon, left the White House with the express purpose of fomenting an intraparty civil war with no apparent objection from the president, if not his tacit approval. So Republican lawmakers, and senators especially have targets on their backs, face the prospect of bloody primary battles too. Sens. Jeff Flake of Arizona and Bob Corker of Tennessee were both charter members of the Bannon target list before they decided not to bother with re-election.

All of this might be tolerable if it came with a raft of legislative achievements. But no border wall is forthcoming and the administration has not produced an infrastructure plan; repeal-and-replace proved to be a dizzying failure (punctuated by the fact that Obamacare is suddenly a boon for Democrats: Health care was the dominant issue in the Virginia governor's race while on the same day Maine voters opted to accept the law's Medicaid expansion).

What's left? A tax overhaul (or just a tax cut) has become the final vehicle for all GOP hopes and dreams but significant policy divides remain. Republicans are publicly staking their majorities on passing that, if nothing else. Tuesday's fiasco "simply means we've got to deliver," House Speaker Paul Ryan said Wednesday. The GOP message is now: They will succeed because failure is not an option; they will not fail because success is necessary. You might recall this tautology from the attempts to repeal the Affordable Care Act.

All of this leaves GOPers in a political miasma: Critics and swing voters are repelled by what they want to do while their own voters are sullen over their failure to actually do it.

This is the context surrounding Tuesday's elections; that day brought the first real-world consequences of those toxic atmospherics. This is the scene in the movie where, the local fauna become increasingly agitated, the ground issues its first rumbles, prompting the characters to exchange nervous glances.

And again, Tuesday will only amplify things: Boosting Democratic fundraising, speeding Republican retirements and helping push fence-sitting Democratic recruits into the arena.

Here's the caveat portion of the column: Thanks to both the fact of GOP-dominated redistricting and inefficiently-distributed Democratic voters ("Where do Democratic voters live? Urban areas and college towns," Cook quipped. "Where do Republican voters live? Everywhere else."), the House playing field has a strong Republican tilt; and Democrats are defending Senate seats in 10 states that Trump won last year.

All of this mitigates against Democrats. Cook, for example, said that while "every wave I've ever seen started looking somewhat like this," the GOP structural advantages mean that what might typically be a 30-65 seat Democratic tsunami could end up being closer to a 20-30 seat gain. Democrats need 24 to regain control of the House.

So the best summation of where things stand a year out from the 2018 midterms is probably that events are aligning in a way that is necessary for a Democratic wave but we cannot know whether they are sufficient.