President Obama is expected to announce by mid-September whether he will circumvent a recalcitrant Congress and press ahead with immigration reform on his own terms. "Executive action," as it's come to be known, could be as robust and consequential as providing de-facto earned amnesty for millions of undocumented immigrants now living in the shadows. That decision would reverberate widely. Democrats have usually been afraid that if Obama decided to showcase the apogee of presidential power, the counter-reaction among conservatives and revanchists would cost Democrats an intolerably high political price.

Now, though, after all the midterm primaries are done, as the cluster of Democratic congressional seats that appear in jeopardy continues to grow, some in the party are rethinking their reflexive fears. They've come up with a scenario where an aggressive Obama executive order on immigration helps them keep Republican margins in check in November, helps them keeps the Senate, and even gives them a chance to take control of the House.

It's as far-fetched as vegan food is tasty, but here's the basic plot line:

In September, Obama signs an executive order that expands the Deferred Action on Childhood Arrival program (DACA) to cover an additional hundreds of thousands, if not millions, of undocumented immigrants, including parents and family members of DREAMers, and older DREAMers (who were over 30 years old when Obama first announced the deferrals).

The GOP, which voted to end DACA before the start of the August recess, would respond by "exploding in anger," which is in quotes because their anger is as much for show as it is about any principled solution to the immigration crisis.

The Republican voting base would demand that the House GOP punish Obama for acting like a king. Nativists would get traction on talk radio. The debate inside the party would be about how, not whether, to respond, and quickly.

And — look at this — they have ten working days to figure out a way to fund the government for the rest of the budget year. That's a coincidental result of the last major stalemate.

The only way to punish Obama, really, is to punish his constituency, the thinking goes. Punish the people who get the most from Obama: So shut the government down, again. (GOP Sen. Marco Rubio has hinted that this might happen.) Republicans might just figure that the GOP is so far ahead in the midterms that they won't face a voter revolt for doing so.

So, let's say the GOP tries to punish Obama by indeed shutting the government down. Again.

The Democratic scenario has Republicans underestimating the price of such a move. Indeed, Democratic focus groups consistently show that the most unpopular thing the GOP can do, the one thing that will make people who are too disgusted to vote, vote, or who are capable of changing their vote to change their vote to the other side, is to shut down the government again. It is that unpopular.

Latino turnout might increase a little, and there are some House races where this might matter, but for the most part, large quantities of voters would respond unfavorably only to the government shutdown by punishing Republicans. Democrats won't reward Obama in droves for doing something on immigration, but they may well turn out to punish Republicans for shutting down the government.

Many Democratic constituencies — younger votes, single women, Latinos, Asian-Americans, and other members of the Obama coalition —don't vote in midterm elections. This isn't because they want to punish the Democratic Party; it's because they tend to cluster in places where midterm House elections don't matter as much, and because the midterm voter profile — old, white, rich — is, of course, a self-fulfilling prophecy.

So: Go big on immigration. Wait for the GOP counter-reaction. Quietly pray for the government to get shut down. Use it like a cattle prod to wake voters up just before the midterms.

That's the last, best hope for Democrats.