Cold reality is setting in for the GOP: The only thing standing between a serious electoral setback and a truly historic shellacking in November might be Special Counsel Robert Mueller's sprawling investigation into Russia's interference in the 2016 elections.

It's easy to lose sight of this in the day-to-day Choose Your Own Misadventure cacophony of the Trump White House, but the Mueller investigation really is a guillotine blade set to decapitate the administration and congressional Republicans at any moment over the next six months. The White House knows it, which is probably why the president is yelling into the Twitter void about tariffs and trade wars as senior aides continue to disappear back into the private sector with the names of expensive lawyers stenciled on their palms. At this rate, the Trump administration is going to be like some sitcom that replaces every single cast member except the star and dares you not to notice.

How worried should congressional Republicans be about the Russia probe? The gamut pretty much runs from the total exoneration of the president, his aides, and his presidential campaign, all the way up to crimes so malignant and undeniable that they lead to impeachment even while Republicans control Congress.

Here are four possible ways the investigation could end, and what they mean for the shape of our politics.

1. The perfect storm

While we are unlikely to ever be treated to tapes of President Trump gallivanting with prostitutes in Moscow or fielding furtive calls from Vladimir Putin from a campaign stop in Michigan, that doesn't mean Mueller doesn't have evidence of deliberate cooperation between the Trump campaign and Russian agents. It is already clear that campaign aide George Papadopolous had advance knowledge of Russian hacking operations into the DNC and John Podesta, and it is unlikely that he did not share that information with other members of the campaign team, including Donald Trump Jr., Jared Kushner, and digital director Brad Parscale. The extent of the campaign's deliberate collusion with Russian crimes may be even more sweeping than we currently imagine.

If Mueller charges multiple senior members of the Trump campaign with felonies directly related to Russia's disinformation efforts and presents any evidence at all that then-candidate Trump knew about these machinations, his presidency is effectively over. Those indictments will make the obstruction of justice charges that are all but certain to be leveled at the president himself as well as other senior aides much harder to shrug off as the side effects of an illegitimate investigation. It never gets old to point out that the president, like a badly written Law & Order villain, already admitted to obstructing justice in the Russian investigation when he told Lester Holt on national television that he fired FBI Director James Comey to end the agency's probe. Subtle our president is not. Mueller has been questioning key witnesses about the events leading up to Comey's firing, as well as the events surrounding the June 2016 Trump Tower meeting between Trump's Fredo contingent and Russian emissaries.

But collusion and obstruction of justice could also be paired with indictments for major financial crimes inside the Trump Organization and the interests controlled by other key Trump advisers like Kushner. We know that Mueller's marching orders included the right to investigate unrelated crimes discovered as part of the Russia investigation, and he seems to be doing just that.

Both Jared Kushner and Ivanka Trump have long histories of shady dealings both in the United States and overseas. And the president himself still refuses to release his tax returns or explain why, to choose just one small example, units in the Trump Soho building were sold well above market value to shell companies paying cash. Ivanka and Don Jr. escaped charges of misrepresenting that same property to buyers after lawyer Marc Kasowitz made a donation to the judge's re-election campaign. There's the $184 million bailout loan that Kushner Companies received from an outfit called Apollo Global Management to prop up a Chicago high-rise after Kushner met repeatedly with Apollo co-founder Joshua Harris at the White House. At this point it would take an encyclopedia series to document the full list of this family's sketchy connections over the years, and it is preposterous to imagine that none them ever resulted in an actual crime.

The fallout from this scenario would be almost unimaginable. Not only would it instantly become the gravest political scandal in American history, but it would also destroy what remains of the president's plummeting popularity. It could trigger the chain of events that lead to his impeachment and removal from office. After all, even Republicans in relatively safe districts who have dutifully hollowed out their souls for this president will reach a point where their political futures become linked inextricably with his. Most people do not, in fact, choose to go down with the ship, although many die anyway when they get pulled into the deep by the wake. The perfect storm would probably just force Republicans to choose how they want to die politically, and many might make the calculation that history will remember them more kindly if they do the right thing before disappearing under the surf.

2. Much ado about obstruction

What if the Mueller probe ends up exonerating most, if not everyone, on the Trump campaign? Perhaps it indicts a handful of clownish hangers-on like Carter Page or Roger Stone for election-related malfeasance, but leaves the inner circle — Reince Priebus, Kellyanne Conway, and the Trump family — relatively unscathed. Some Trumpist analysts like to cling bitterly to the idea that the president might survive an obstruction of justice charge if it is not paired with significant campaign wrongdoing.

After all, this is an extensive investigation that will soon hit the year mark, which itself was preceded by an ongoing FBI probe into the president's campaign and its ties to Russia. If they both yield nothing much of substance except that the president surrounded himself with a gaggle of hapless yutzes who lied to cover up their involvement in unrelated schemes, it will give fresh confidence to Trump's apologists that this has all been an enormous waste of time.

We don't have much to go on in thinking through the fallout of such serious charges against a sitting president. Richard Nixon resigned before the obstruction of justice charges recommended against him by the House Judiciary Committee could be considered by Congress, and Bill Clinton's popularity allowed him to benefit, in the short run, from what was widely regarded as a partisan impeachment based on an invasive inquiry into the president's personal life.

President Trump enjoys no such pre-existing popularity, nor is the Russia probe itself viewed as a piece of partisan overreach by the vast majority of voters. Most people are probably underestimating the political damage the president will suffer as a result of these accusations. For other offices, the effects of scandals are devastating. A 2013 paper found that even controlling for factors like the underlying partisanship of a district, scandals reduced the election margin of sitting congressional incumbents by 14.5 points. It also found that turnout spikes in the first post-scandal election, but that the benefit of that turnout "appears to accrue exclusively to challengers." Not only that, but the scandal-plagued incumbent, even if he or she survives the following election, does not return to pre-election levels of public support for 4-6 years. Obstruction of justice charges, therefore, will mean trouble for the GOP not just in 2018 but also in 2020, even if Trump remains in office tweeting "NO COLLUSION" every 20 minutes for the next three years.

3. If you build it, they will launder your money

Another scenario involves the president's exoneration in the whole matter of Russian interference in the 2016 election, a finding that no one in his administration acted knowingly to obstruct justice in either the FBI investigation or the Mueller probe, but instead some revelation of criminal behavior in the recent past of the Trump Organization. This is almost certainly a much better scenario for the president than being accused of obstruction of justice. After all, the president settled a fraud case related to his fake university for $25 million a month before he took office, and the collective reaction in D.C. and the country at large was a yawn.

Most Trump supporters probably already believe that the president engaged in unsavory business practices, and that as long as he keeps triggering the libs, they couldn't care less. The president almost certainly can't be prosecuted while he's in office, especially for crimes committed while he was still a crusty caudillo overseeing his empire of tackiness, and the revelation that Kushner or even Ivanka is a double-dealing huckster out to defraud investors will probably just result in their swift departure from the White House. Republicans in Congress, who have so far been willing to watch quietly as this nightmare platoon of brazen looters makes off with the executive branch office by office, are unlikely candidates to decide that laundering money for Kazakh gangsters is the crime that should push Trump out of office. The president might even get a small, if illusory, approval bump for dodging collusion charges. But if the charges involve something truly grotesque, like complicity in human or drug trafficking, all bets are off.

4. The dream clean scenario

Of course, it is still possible, though seemingly unlikely, that the president will walk away from this imbroglio without being accused of election wrongdoings, financial misconduct, or obstruction of justice. It is certainly possible that campaign aides who ended up doing the bidding of Russian cut-outs did so "unwittingly" (in the language of Mueller's recent indictments of 13 Russian nationals accused of conspiring to defraud the United States). That would be embarrassing for them, but certainly not a prosecutable crime. And it's possible that Mueller, while strongly suspecting that the president intended to interfere with the Russia investigation by firing Comey or concocting false statements to explain away the infamous Trump Tower meeting between Kushner, Trump Jr., and Russian agents, lacks the concrete evidence to make the accusations. It is also possible that Mueller's incidental investigation of the Trump Organization's dealings finds nothing actionable, or that any violations of the law were committed too long ago to be prosecuted. While it strains credulity to think that Mueller won't turn up some embarrassing tidbits about the Trump family business, this is not a group of people capable of being brought down by shame alone.

If this is the outcome of the inquiry, it will be nothing short of demoralizing for the left. But would exoneration save the GOP? The impact would depend on the one big question hanging over everything: Are the president's scandals already baked into his dreadful approval ratings, or are there a significant number of voters, particularly independents, who might change their appraisal based on the outcome of Mueller's investigation? If it's the latter, exoneration for the president and his key advisers might give congressional Republicans enough ballast to narrowly hold onto the House and even increase their margins in the Senate.

How likely is this total exoneration scenario? That depends on how likely it is that everyone in Trump's orbit is lawyering up, lying to the FBI, running as far away from the Potomac as possible, forgetting all their conversations with Russians, and climbing over one another to knife their rivals in the back for the nearest Politico reporter, all for absolutely no reason whatsoever.

What's more likely is this: They did it and they covered it up and pretty soon the president and his party are going to pay for it in a way that they'll really have trouble forgetting the next time they find themselves under oath.