In December, polls showed the plan was deeply unpopular. This was when the bill was grinding its way to passage in Congress. Its opponents were relentlessly campaigning against it, while the bill’s supporters were busy negotiating — and perpetually dissatisfied with its latest form — and didn’t defend it in a meaningful way. Most voters thought they would see a tax hike, even though they were probably going to get a tax cut.

Today, the politics of the issue are very different. The attacks on the bill have relented now that it has passed. A steady stream of good economic news, including announcements of bonuses and raises that some corporations are attributing to the tax cut, have amounted to a substantial if belated public relations campaign for the bill. It is also possible that voters have realized they’ve gotten a tax cut.

The bill isn’t exactly staggeringly popular, according to more recent polls that still show that more Americans disapprove of the bill than support it. But it’s polling a lot better than it did a month ago and even fairly well by the standards of President Trump’s approval rating.

Regardless of how it polls over all, there can be little doubt that many Republicans, who might have been dissatisfied with the accomplishments of the Republican Congress, have now gotten one of their biggest wishes.

Does that add up to a lasting change in the national political environment? Who can say. What can be said, fairly confidently, is that two weeks of good polling for the Republicans are not enough to declare that such a shift has taken place.

Take a look at two ways of calculating the generic ballot polling average. Both account for the biases of various pollsters, and give more weight to higher-quality and less frequent pollsters. In light gray is a sensitive estimate — the sort of polling average you would use heading into Election Day. It doesn’t care much about polling from a few weeks ago. Wednesday’s Monmouth poll, which showed Democrats ahead by just two points, is far and away the most important single data point in its estimate.

In dark purple is a less sensitive estimate. It’s as sensitive as the Upshot Senate model from 2014 would have been nine months from a congressional election. It’s not sensitive at this stage for a simple reason: Bumps and blips don’t tell you too much this far from an election.