Universal health care drains PC, triggers fights, and saps floor time.

At the end of 2016, after the election of President Donald Trump, Republicans across the country were elated by the perceived inevitable, imminent repeal of the Affordable Care Act (ACA). Democrats mirrored these expectations with despair.

As I wrote at the time, however, political realities and policy complexities have a way of colliding with such irrational exuberance. The infamous demise of the “Repeal and Replace” campaign bore out these verities.

It didn’t take long for the pendulum to swing. Comparably high expectations have arisen among Democrats that Medicare for All, or one of its many siblings or cousins, could pass in 2021.

While conventional wisdom, and some presidential candidates, have already begun to temper these expectations, my goal here is to document five reasons why Medicare for All (M4All), Medicare buy-in, or federal public option legislation cannot pass in the near future. My hope, in doing so, is that we Democrats spare ourselves the precious time, internal acrimony, and political fallout that Republicans faced when their lofty ACA repeal promises went unfulfilled.

Reason No. 1: The 2020 Election

This one is perhaps the most obvious but an appropriate place to start. President Trump probably has about a—gulp—50 percent chance of winning reelection. (Online punters tend to put his odds higher.) While it’s fair to respond that Democrats are assuming a presidential victory, at least, when debating the nuances of Medicare for All, suffice it to say we should probably refrain from eating each other alive over it just yet.

That still leaves the Senate election, which presidential candidates and the rest of us ought to consider carefully in stoking expectations. Even if 2020 is an otherwise favorable year for them, the Senate electoral map poses an uphill climb for Democrats, who must net three seats to take control of the chamber (assuming they win the White House). Only two Republican senators are running states won by Hillary Clinton, and one Democrat, Doug Jones, is running in deep red Alabama.

I don’t think you can reasonably put the odds of the Senate flipping at over 50 percent either, which if combined with the at best even odds of taking the White House, leaves Democrats with relatively dim hopes of controlling the policy-making apparati of Washington come 2021.

Still, for the sake of our collective pleasure and edification, I am willing to cede you, my skeptical friends, both of these planks. Let’s assume Democrats do win the White House and Senate, albeit with a presumably razor thin (and politically tenuous) hold on the latter. I’ve still got four concrete legs to my theory’s stool, with the first being, naturally, …

Reason No. 2: The Senate

… the darn Senate. The ire of every majority party and darling of every minority one. The graveyard of bold, bright, and hotly partisan ideas. Love it or hate it, the institution and its norms are here to stay.

The first and most important thing to note here is that M4All or anything resembling it is highly unlikely to qualify for the budget reconciliation process, which would reduce the vote threshold for Senate passage from 60 to 50.

While it probably warrants its own post, the crux of this point is that only policies that have a meaningful budgetary impact qualify for the budget reconciliation vehicle. Because all M4All-ish proposals include inserting Medicare, a Medicare-like program, or a Medicare-like public option into the commercial market, fairly extensive policy care and craft must be afforded to ensuring the rules that apply to it mirror those that apply to other sources of coverage.

Failure to do so will highly likely lead to adverse selection (meaning an imbalance of higher-risk enrollees will gravitate to one of the options, presumably, in this case, the Medicare-like one) and precipitate the demise of the new coverage regime. The problem is that the predominant impact of these market-stabilizing policies is not budgetary, and thus they cannot be included in budget reconciliation bills.

Another change that would be necessary under any expansion of Medicare to the non-senior market would be the addition of new benefits not deemed necessary to the existing beneficiary population, such as contraception. Pediatric benefits also, for obvious reasons, get short shrift in Medicare. Adding these benefits to make the Medicare-like coverage suitable for the newly eligible people is also unlikely to qualify for reconciliation.

While the smart and savvy brain trust of lefty policy wonks does have a shot at cracking this code and concocting an M4All bill that protects market stability and qualifies for reconciliation, we ought to accept that is a good bit less than probable.

Reason No. 3: Democrats Will Find Compromise Difficult

Even if Democrats can use budget reconciliation to enact an M4All-related policy, at least 217 members of the House of Representatives and 50 senators will need to agree on what that policy is. Who would be the fiftieth vote for this sweeping reorientation of our health care system? Joe Manchin of West Virginia? Jon Tester of Montana? Doug Jones from Alabama?

Please spare these senators your hate mail. Their ability to win in overwhelmingly Republican states will be the reason Democrats take the Senate, if they indeed do. Asking them to support the same bill that would need to be embraced by Bernie Sanders and Alexandria Ocasio-Cortez won’t do them or the Democratic Party any good and, suffice it to say, can’t be counted on.

Keep in mind the perilous path the ACA took to enactment, barely attaining passage through each chamber after 15 months of extensive debate and wrangling, and that was with the support of the vast majority of the health care industry. Will Democrats, some emboldened and others wary, be able to forge consensus in a crucible of stakeholder opposition?

Reason No. 4: Other Priorities

Having spent the first 15 months of their control of Washington eight years ago on health care, and paying for the political fallout from that ever since, will Democrats choose to go down the same path in 2021?

I can still remember then-candidate Barack Obama, during a primary debate, saying health care would be one of the first two issues he would address as president because he thought it would be “easy.” Later, his advisers hopelessly tried to build the impression reform would be signed and sealed by July of his first year.

We will know better in 2021. If Democrats go down the M4All path, it will be extraordinarily contentious, protracted, and all-consuming. Many in the party and otherwise across the country would likely prefer to see Democrats prioritize other issues that have stood on the sidelines for more than a decade.

As tidily outlined by Matthew Yglesias, not exactly a wilting flower on the left, issues such as climate change, democracy (voting rights, and so forth), and immigration, deserve renewed attention, especially after the assaults each has suffered under the dominion of President Trump.