In the House, Democrats are inching ever closer to impeaching President Trump. Some are even pushing for drafting articles of impeachment by Thanksgiving and, potentially, sending proceedings to the Senate by early next year. If the charges reach the upper chamber, at least 20 Republicans would have to join every Democrat in voting guilty in order to reach the two-thirds supermajority needed to remove the president from office.

So now begins the reading of the tea leaves and the careful scrutiny of every Republican senator’s statements (or silence). Will Republicans finally break with Trump? We may not know until it happens. But be forewarned — if it does happen, it will likely take us by surprise. After all, political science has shown us that big political changes often come suddenly, after long periods of stasis. Looking back, it seems like of course the Soviet Union was bound to collapse. But up until the moment it did — and remember, it fell all at once — almost nobody predicted it.

Why Republicans are unlikely to turn on Trump

It’s not exactly a secret that if congressional Republicans could hold a secret-ballot no-confidence vote, they’d probably vote to oust Trump. There’s just one problem with that logic (aside from the fact that it’s not how our democracy works): Private preferences aside, congressional Republicans actually have some very strong incentives to support Trump publicly, at both the individual and collective level.

Take those who have openly challenged the president. The few, like former South Carolina Rep. Mark Sanford or Alabama Rep. Martha Roby, have faced primary challengers as a result — Sanford lost his renomination bid, and Roby was forced into a runoff. Others, like Arizona Sen. Jeff Flake simply retired, fearing tough reelection prospects. And this all adds up, contributing to the perception that Trump’s popularity is un-dentable among GOP voters. Republicans likely won’t individually take on Trump, unless, of course, his approval rating tanks and he becomes a liability to the party. But that’s only likely to happen if his fellow Republicans all turn against him. And therein lies the rub.

Collectively, Republicans want to keep Trump popular so they can keep winning elections. In our era of increasingly nationalized politics, most Republicans can’t run independently of the president, even if they want to. Perhaps recognizing this, many have instead tied themselves more closely to him. Trump defines the Republican Party brand as president, so if Trump is unpopular, the Republican Party is unpopular, which would likely spell steep electoral losses for the party.

The only way this dynamic changes is if the entire Republican Party apparatus (not just politicians, but also media commentators and surrogates) turns on Trump en masse. But for this to happen, somebody still has to speak up first, and others have to follow. But it could happen. Let’s use political scientist Timur Kuran’s classic work, “Private Truth, Public Lies: The Social Consequences of Preference Falsification,” as a guide to understanding major political transformations. He argues that political regimes can persist despite being unpopular, which is why a government overthrow, when it does come, can often seem so sudden.

Consider the Arab Spring, which began with one Tunisian vendor, who protested being mistreated by government officials by setting himself on fire. His death triggered a series of events, and a month later, the long-unpopular authoritarian Tunisian president fled the country after more than 23 years in power. A few weeks later, protesters in Egypt ousted their own long-serving authoritarian leader. What looked like ironclad power collapsed in a matter of weeks. Why?

Kuran argues in his book that protests need a critical mass of supporters in order to force change. The logic is that there’s safety in numbers, so if multiple citizens rise up in protest of a regime, it signals that it’s OK to protest — which can cause decades-old regimes to collapse all at once.

Signs the GOP might soon abandon Trump

How does this all factor into the politics of impeachment, exactly? Well, the basic logic is the same — right now, Republicans in Congress aren’t willing to stand up to Trump, so there’s no sign that someone’s willing to be the first to go. Without a bold leader, there are no bold followers. But without the promise of bold followers, there are no bold leaders.

Who goes first matters, too, because if we’re talking about a monumental sea change, it isn’t moderate Republicans like Sen. Susan Collins of Maine or Sen. Mitt Romney of Utah who will lead the GOP parade.

Rather, it’s rank-and-file Republican senators up for reelection in solidly red states, like Bill Cassidy from Louisiana or Jim Inhofe from Oklahoma, whom you should watch. If they waver, that will signal that Trump’s days are numbered. Of course, the rub is that neither have spoken out against Trump — in fact, they’ve stuck by him — but that’s the point. If Republicans do abandon Trump over impeachment, it will be because of the senators least likely to strike out against Trump balked.

Each new development potentially changes the calculus, too. For instance, last Tuesday, the Senate unanimously passed a nonbinding resolution calling on the Trump administration to release the whistleblower complaint that alleged the president had tried to coerce the Ukranian president to investigate Democratic front-runner and former Vice President Joe Biden. The resolution signaled a surprising bipartisan willingness to let more information out. But by Thursday, after the whistleblower’s complaint went public, most Republicans had already rallied around talking points that questioned the motivations and veracity of the whistleblower, instead of criticizing Trump. The short-lived moment for a cascade passed almost as quickly as it had come.

But if you’re looking for another moment when Republicans might break with Trump, look for an event like last Tuesday. Moments like that can create uncertainty and situations where the ground can shift quickly. For most congressional Republicans, this is no doubt a frustrating state of affairs. Few presumably relish defending Trump against the increasingly indefensible. But this is where the party is currently stuck.

Even if most Republicans believe Trump is bad for the long-term health of the party, they have a major here-to-there problem. Turning against Trump seriously jeopardizes their immediate political fortunes. So all signs point to Republicans sticking it out with Trump. That means they’ll continue to find new ways to dance and dodge, and eventually, they’ll probably even vote to exonerate him in a Senate impeachment trial, if things come to that. Senate Majority Leader Mitch McConnell, in particular, has no incentive to break from Trump. After all, his plan for grinding out partisan victories with Trump in the White House involves the same zero-sum attack politics as the president uses. Not to mention, McConnell is also among those red-state Republicans up for election in 2020.

If there is a Republican cascade against Trump, in retrospect, it will look inevitable, as if the steady drip of revelations and testimony was always destined to reach that final dramatic tipping point. But a note to future historians: As of this moment, it does not look inevitable at all.

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