Analysis by Gregory Krieg

PHILADELPHIA (CNN) -- The special election contest in southwest Pennsylvania will come to an end on Tuesday night and, though the winner remains in doubt, the post-election spin pretty much writes itself.

A new Monmouth University poll out Monday afternoon shows Democrat Conor Lamb leading GOP candidate Rick "I was Trump before Trump was Trump" Saccone, but the margin is slight -- meaning political operatives and pundits are preparing for all eventualities.

Live Results: Pa. US House District 18 Special Election

That includes the most powerful political pontificator in the land -- President Donald Trump. According to Axios, he is not-so-privately dumping on Saccone and his campaign, calling the Republican "weak." Meanwhile, Democrats are champing at the bit, prepared to declare Lamb's victory (or narrow defeat) -- in a district Trump won by nearly 20 points in 2016 -- a canary in the GOP's congressional coal mines.

Here's what you can expect to hear beginning around the time the beers crack on Tuesday evening...

Lambs wins! Republicans are doomed in November/Saccone was a terrible candidate

Dems' take: Republicans have dominated this district for 15 years. Former Rep. Tim Murphy, who resigned in October after it was revealed he'd asked his lover to get an abortion, ran his last two races unopposed by a Democrat. And now, this!

Saccone's struggles, especially on the fundraising front, and eventual loss show that Trump's unpopularity is pulling down his party, while enraging and engaging Democrats. This is the second consecutive high profile race, after the Alabama US Senate clash, in which Trump's preferred candidate fell short even with the President's blessing and an overwhelmingly red electorate.

GOP take: Saccone was a poor candidate, while Lamb was a very good one. Lamb also had the benefit of being able to tack to the center, basically running as a moderate Republican ("Republican lite"), because the unique nature of the race cut off any potential challenge from his left. Enjoy it now, Dems -- November will be a lot more complicated.

Saccone wins! Republicans' problems have been overstated/Dems can't get over the hump

GOP take: ... is not much different than if Saccone loses. At least among party people. From Trump, though, there will be a declaration of total victory. That line from Saccone about being like Trump will probably end up in a presidential tweet. This past Saturday night's rally will also likely be highlighted as the event that put a laboring Saccone over the top.

Also, tariffs. The white working class sees a President on their side and, despite a whole bunch of spending by Democrats (and groundwork by local unions) to convince them otherwise, they sided with Trump's guy.

Dems' take: Again, familiar fare. Republicans have dominated this district for 15 years. No Democrat challenged Murphy the last two cycles and Trump (and Mitt Romney and John McCain before him) won it handily -- in the 20-point range -- in presidential years. It took Trump less than two years on the job to turn it into a toss-up.

Oh, and about the fundraising. Yes, it's true Lamb outraised Saccone. But that doesn't account for outside groups, which rescued Saccone (total bucks dedicated to electing him way outpaced Lamb). Republicans won't be able to dedicate those kinds of resources to every endangered House seat this fall -- and there are many.

Who cares, really?

The losing side will surely drift this way as the hours pass on Wednesday. They'll note that Pennsylvania's congressional map is about to change, and in a way that favors Democrats. The winner on Tuesday will, if he jumps back in, be running for a different seat come November, perhaps in the state's newly drawn 14th or 17th districts.

A lot can happen between then and now, but by January of 2019, Saccone and Lamb could be in the same queue, both waiting to be sworn in to the 116th US Congress.

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