Senate Majority Leader Mitch McConnell (R-Ky.). (Jabin Botsford/The Washington Post)

Obamacare repeal? Dead.

Tax reform? Dead and demoted to tax cuts, now also on life support.

Republicans may have unified control of government, but they seem curiously incapable of getting major agenda items through.

Maybe it’s because Republicans have insisted on cutting out Democrats and doing things unilaterally. Or at least they had been until Thursday, when a bipartisan coalition of 24 senators signed onto a bill to patch up Obamacare. While President Trump and congressional Republican leadership remain skeptical about working with the enemy, this could be the start of a turnaround for the GOP.

To be clear, "bipartisan" ideas are not necessarily "good" ideas. Sometimes a policy that both parties support turns out to be a huge mistake.

As a political matter, though, it can be extremely useful for the majority party to get buy-in from the other side, for three reasons.

First, it offers political cover to do necessary but unpopular things.

If you actually want to reform and simplify the tax code, you have to close loopholes benefitting some constituents. If you want to cut rates without increasing deficits, you need to find money elsewhere, either through spending cuts or other tax increases. Which some affected group is going to be unhappy about.

Likewise, if you want to wring money out of the health-care system, you likely have to inflict pain on someone, whether it’s patients, providers, insurers or drugmakers.

In other words, despite what Trump may claim, few policy changes are really win-win. There’s almost always going to be at least one loser, who will likely be loud and angry.

And if your party and your party alone takes ownership of these changes, that loud and angry loser is going to direct this rage at you.

Senate Majority Leader Mitch McConnell (R-Ky.) surely knows this. It’s one reason he refused to work with President Barack Obama on almost any major policy initiative. That way, whenever bad things happened, Republicans could throw up their hands and proclaim: Don’t blame us!

And in fact Republicans said this all the time, even over bad stuff unrelated to any Democratic policy decisions.

Now, surprisingly, McConnell has boxed in his own party in the exact same way.

He declared his intention for Republicans to govern solo, both by crafting bills of major consequence in secret, without Democratic input, and by attempting to pass those bills through a process requiring zero Democratic votes.

In so doing, he’s forced Republicans to take the heat for every controversial decision Congress makes.

No wonder, then, that the party appears to be giving up or watering down basically every major pay-for in their tax overhaul. These include the border-adjustment tax (remember that?) and full elimination of the state and local tax deduction.

Republicans are similarly stuck with the blame for everything that goes wrong in the health-care system. A majority of Americans already say that Trump and congressional Republicans are responsible for any problems with Obamacare moving forward because they're the ones in charge, according to a recent Kaiser Family Foundation poll.

And when the broader economy softens — which it inevitably will — Republicans will again get stuck holding the bag. Because they hogged the bag.

Second, if Republicans worked with Democrats to find some middle ground and pass their initiatives through so-called regular order, the Grand Old Party wouldn’t be so easily tripped up by hostage takers.

Right now, Republican leadership is beholden to the craziest members of its own party. Someone such as Sen. Ted Cruz (R-Tex.) knows he can make unreasonable demands because McConnell can’t afford defections.

And of course giving in to fringe demands can cost leadership the votes of more moderate members of their caucus, a dynamic we saw during the Obamacare repeal efforts.

Aiming for a bipartisan coalition of the middle 60 or so votes, instead of requiring the vote of nearly every Republican, would avoid giving undue power to any one legislator (crazy or otherwise).

Finally, if the majority party successfully achieves meaningful support from the minority, it’s less likely that a major policy initiative would be undone or sabotaged when the balance of power shifts.

That's a lesson the Democrats have of course learned with Obamacare, which passed along party lines (despite Obama's efforts to woo Republican votes).

Presumably GOP leadership fears that working with Democrats on an Obamacare fix could leave Republicans vulnerable to being primaried from the right. But what’s a bigger threat: some criticism for playing nice today or facing millions of uninsured Americans a few years from now?