After a secretive, whirlwind negotiating session, Capitol Hill Republicans have agreed on a tax package. They’ve taken this from the Senate version and that from the House version, and it looks as if it’s going to become law.

But it doesn’t add up, and the American people know it. The bill is wildly unpopular: Approval for it languishes around 30 percent in polls. In fact, it’s the most disliked piece of major domestic legislation of the past quarter-century — most disliked, that is, except for the Obamacare repeal undertaken this past summer by this same Congress. That effort, which failed only because of Senator John McCain’s dramatic 1 a.m. thumbs down, was polling at 23 percent.

On what basis do I assert that these two bills are the most unpopular pieces of major domestic legislation of the past quarter-century? On the results of researchconducted by Chris Warshaw, a political scientist at George Washington University who specializes in studying the link between public opinion and political outcomes — whether the government is doing what its citizens want it to do.

It struck him, Professor Warshaw explained to me recently, that the Republicans of this 115th Congress had spent the entire year trying to pass two enormously unpopular acts. He got curious about whether any party had tried something like that before in recent history. He examined 15 pieces of major domestic legislation going back to 1990 and studied 17 polling firms’ approval ratings for those bills when they were being voted on.

After crunching the numbers, he found that the tax bill and the Obamacare repeal effort were at the bottom on the list in popularity, ranked 14th and 15th. But here’s what was even more interesting: Of the 15 bills, nine had an approval rating above 50 percent at the time they passed or failed. And of those nine, eight pursued what could broadly be defined as liberal goals, like gun control and environmental protection….

So there you have it. In 27 years, Republicans have passed one popular conservative law and spent most of that time voting against things that clear majorities of Americans wanted. If they weren’t serving Americans, whom were they serving? And how have they gotten away with it?

The answers to both questions, alas, are depressingly familiar. They are serving their megarich donors and the most extreme elements of their base. And they get away with it because of the way they’ve gerrymandered House districts, because of an ideological right-wing media that obfuscates facts and because the one thing they’ve done astonishingly well is to make a big chunk of the country hate liberals.