At the frazzled conclusion of the seven-year Republican quest to repeal Obamacare, Senate leaders and President Trump are resorting to a simple message: You have to do it.

“Inaction is not an option, and frankly, I don’t think we should leave town unless we have a health insurance plan,” Trump told Republican senators as they met for lunch at the White House.

The Republican ambitions suffered a major setback Monday when four senators refused to vote for their party’s bill. A backup plan, to partially repeal the health care law without replacing it, also lacks the votes. Yet Mitch McConnell is still trying to pass something, leaning on two arguments: Obamacare is failing, and Republicans promised for seven years that they would repeal and replace it.

But Obamacare, while imperfect, isn’t failing. And the argument that even passing a devastatingly unpopular bill is better than doing nothing doesn’t hold up, based on the available political science. Recent research suggests that for political parties that take power, overreaching — going too far in imposing their ideological preferences — is a bigger threat.

No single issue will define next year’s election or the one after that. Right now, the American economy is in relatively good shape, yet Trump’s approval rating is dismal. Those variables have a longer track record of driving votes than health care.

But both parties are threatening to make health care a defining issue of next year’s election. Whether they squabble over a deeply unpopular new law — or Republicans’ failure to pass one — will be decided in the coming days.

Why doing something isn’t necessarily better than doing nothing

Vice President Mike Pence summarized the Republican leadership’s position on Wednesday morning: “Inaction is not an option.”

Every day Obamacare survives is another day the American economy & families struggle. @POTUS is right - inaction is not an option. https://t.co/7uv5rpuaix — Vice President Pence (@VP) July 19, 2017

But a look at the political science evidence suggests Pence, McConnell, and Trump might be wrong about that.

Andrew Hall, a political science professor at Stanford University, and his colleagues reviewed state legislatures in a December 2016 paper to explore widely held conventional wisdom: Legislative majorities pursue policies intended to improve their chances of winning again in their next election.

They found something different: that parties in power might actually overreach, pursuing policies so far in one ideological direction that they invite political backlash in the next election.

“Majority parties, in state legislatures at least, seem to actually have an electoral disadvantage — if you become the majority one year, you have less than even odds of being the majority party later on down the line,” Hall told me. “We speculate that it might be because the majority party can't resist pulling policy ‘too far’ toward itself.”

Obamacare itself could be instructive. There is evidence, though far from definitive, that voting for the 2010 health care law was a political headwind for Democrats in the following election.

“The real problem for many House Democrats was most likely the Democratic agenda,” another group of Stanford researchers wrote in April 2011, hoping to explain why Democrats had underperformed their electoral projections in the previous election.

As for how this applies to the Republican crusade to repeal Obamacare now that the party controls the federal government, Hall said it would be hard to say for sure. But if you were to take away a lesson, it’s that passing something for the sake of passing it is a strategy with deep risks.

“Maybe it all suggests that sometimes parties ram things through even though they know it will cause some short-term electoral harm,” he said, “either because the members genuinely want the policy, their base compels them to do it, or because they don't believe/understand the consequences.”

The first possibility is belied by the difficulty Republicans have had coming up with a policy they can agree on. The third is certainly possible: Republicans might be blinded by years of running against Obamacare and winning elections.

The second scenario — satisfying the base — is the crux of the GOP leadership’s argument. But the evidence there is far from clear.

Public opinion certainly isn’t with the Republican bill — with one important caveat

The actual Republican plan to repeal and replace Obamacare, the latest version of which is the Better Care Reconciliation Act, isn’t popular, even among Republicans.

As Axios documented earlier this month, the Republican health care plan appears to be the most unpopular major legislation in three decades — less popular than the Clinton health care plan, the Affordable Care Act, or even the TARP bank bailout.

Here is what a Vox/SurveyMonkey poll found this month:

45 percent of Americans said they would be worse off under BCRA; 35 percent said their situation would stay the same; 15 percent said they would be better off.

Among Republicans, only 35 percent said they would be better off. More Republicans, 48 percent, said they would stay the same, and another 14 percent said they would be worse off.

Just 19 percent of Americans — and only 33 percent of Republicans — said they want to see Medicaid spending cut in the future. The rest want the program’s spending to either stay the same or be increased. The BCRA would reduce Medicaid spending, versus current law, by $772 billion over the next 10 years.

At the same time, Obamacare is more popular than ever. A Fox News poll earlier this month found 52 percent of Americans approved of Obamacare, while only 27 percent supported the Republican health care bill.

But there is one important caveat: While this particular GOP plan is overwhelmingly unpopular, the general concept of “repealing and replacing Obamacare” still enjoys strong support among Republicans.

“If you use the slogan, you’ll get 70 percent of Republicans,” a Republican health care lobbyist and former Senate staffer told me.

That’s almost exactly right: A late-April poll by the Washington Post and ABC News found that 76 percent of Republicans wanted to “repeal and replace” Obamacare rather than “keep and improve” it. That was even after weeks of a contentious House debate and the finding that the original House bill would lead to 24 million fewer Americans having health insurance.

The White House and Republican leaders are still banking on repeal being better than nothing

The persistent appetite for repeal and replace, at least as a slogan, appears to be motivating Trump and Republican leaders far more than the fact that their own base seems apprehensive about their actual plan to do it.

Senate leaders and the White House seem to be making the cynical bet that passing anything will satisfy their voters — as long as they don’t realize what’s actually in it.

Obamacare was clearly divisive upon its passage, but Democrats believed its actual policies would win over skeptics. Republicans now want to do the opposite: rip away those benefits and hope that people don’t realize what has happened.

“Republicans are walking down the same track,” the GOP lobbyist told me. “We repealed it, and therefore you must love [this bill]. What it actually does is irrelevant.”

“Most establishment Republicans think it's worse if they don't pass something. Worse if they fail,” another health care lobbyist told me. “Both options stink — but they would rather be on the side of action than inaction.”

Republicans may also be banking, much as Democrats did when they passed Obamacare, that their bill isn’t actually as unpopular as it seems to be right now.

Here’s how Josh Holmes, a longtime adviser to McConnell, explained the thinking to the Washington Post’s Sean Sullivan:

A poll on a complex legislative issue three weeks after it is unveiled has next to no ability to pick up the lasting sentiment. Conversely, over the course of seven years, Republicans have promised to repeal and replace Obamacare and won multiple elections in large part due to that specific promise. A failure to address a conviction among the base of the Republican Party, seven years in the making, is infinitely more damaging than the ramifications of a three-week snapshot that starts well underwater because of partisan polarization.

This may also help explain why McConnell has sought to assure senators skittish about the deeper Medicaid cuts in later years that those cuts would never actually happen.

But it’s also possible health care isn’t the political force it once was. The Kaiser Family Foundation dug up its polling from the week after the 2016 election and noted a mere 7 percent of Trump voters and 5 percent of Republican voters said health care was the biggest factor in whom they voted for.

You could read that either way: Maybe it doesn’t matter if Republicans pass an Obamacare repeal bill. Or maybe they won’t be punished if they do. Holmes did hint that Republicans could recover from a health care failure.

“I also believe there is a cascading effect to not getting this done that could bleed into other agenda items, which would create a catastrophic narrative in the midterms if that occurred,” he said. “It’s correctable if reversed with something like tax reform, but it would be imperative that it be reversed in a significant and lasting way.”

The evidence suggests that passing anything is far from a surefire bet. But Republicans have convinced themselves otherwise. The next 18 months will answer the question for certain, one way or the other.