This was the one shoe left to drop in the RCP “poll of polls.” A few days ago Republicans reached their high-water mark on the generic ballot during the Trump era. The day before that, Democrats’ lead on the generic ballot dipped to its smallest level of Trump’s presidency. The one remaining benchmark was for Dems to reach their own low-water mark on the ballot. That would be 44.3 percent, which they touched at the very beginning of Trump’s term and then once in February of this year. Yesterday they were at 45.0 percent, seemingly in no danger of bottoming out.

Today? 44.2 percent, a new 16-month low.

Not only that, but their lead is also at a 16-month low — just 4.0 points. As recently as two months ago the Democratic lead was more than double that.

There’s a catch, though. The RCP average is based on the most recent national polls taken. Those polls cycle in and out, obviously: When Gallup or Quinnipiac, say, publishes a new one, it replaces the oldest of the ones currently being used to calculate the average. The newest poll in the average today is … Reuters, which has Democrats leading on the generic ballot by one thin point, 38/37. Reuters is the *only* major pollster, though, to have the Dems below 40 percent. Most have them at 42 percent or better. Today’s data may well be an outlier.

Nor is this the first time recently that Reuters has found an unusually low number for Democrats. Last week it had them at 39 percent at a moment when other respected pollsters like Pew and Monmouth had them at 48-49(!). None of that is to say that Reuters is wrong, but for whatever reason their surveys recently do seem to have a much, much higher of people saying “don’t know” when asked which party they prefer compared to other pollsters. Odds are very good that as we get a fresh batch of new polling from others early next week, Reuters will cycle out of the RCP average and the Democratic generic-ballot share will rise again. This may, in other words, be the low point for Dem polling for awhile, with nowhere to go but up.

There are other reasons to keep midterm expectations “realistic,” shall we say. Polls only tell you how people choose when they’re forced to choose. They don’t tell you who’ll get off the couch in November to go wait on line to vote. Certainly it’s Democrats who have the advantage in enthusiasm. Or do they? Amy Walter:

[T]here are some signs that GOP voters may be catching up with Democrats on the measure of intensity. Well-respected GOP pollster David Winston (an expert on all things House), wrote recently: “New surveys — private and media polls — seem to show that the enthusiasm gap, which has plagued the Republican base for the past year, might, at last, be closing. In our April 28-30 Winning the Issues survey, we asked voters to tell us how likely they are to vote in November on a 1-9 scale, with 1 meaning a voter was not planning on going to the polls and 9 meaning they absolutely would. What we found was good news for Republicans. Both parties are at parity when it comes to self-reported likelihood of voting. Conservative Republicans came in at 8.22 with Republicans overall at 8.16. Democrats, whose enthusiasm for voting had previously topped Republicans, are now at 8.12, with liberal Democrats at 8.20.”

Part of the reason for the increase in enthusiasm is the fact that Republicans now have something around which to rally – specifically an improved economy and tax cut law. It also helps that the president and the GOP-controlled Congress are not currently at war with one another as they were during the health care debate. Back then, congressional Republicans not only lacked substantive accomplishments, but the president was actively calling them out on Twitter as incompetent.

That’s reason for optimism, notes Walter, but tempered optimism. After all, the generic ballot tells you about the overall mood of the country but nothing about swing districts, which is where the House will be won or lost. And Trump’s job approval, while considerably better now than it was late last year, is still pretty stinky. When he was at 37 percent last winter, the GOP was staring at a “red wedding” scenario this November. Now that he’s at 43.6, the risk of a wipeout is much reduced — but not gone. Clinton and Obama were both in the mid-40s approval-wise before their own first-term midterms, notes Walter, and each ended up drowning in Republican waves.