After looking better for a while, prospects for Republicans holding onto the House are dimming again. Photo: Matt McClain/The Washington Post/Getty Images

I try hard not to obsess about day-to-day polling trends. But periodically it’s good to check in on key indicators for the midterm elections, and today represented a bit of a landmark in the RealClearPolitics polling averages. The Democratic lead in the generic congressional ballot (asking respondents which party that want to control the U.S. House of Representatives) hit 8 percent for the first time in nearly four months.

Last time RCP showed Democrats up by eight or more points was in mid-March. Since then the lead slowly trended downward, hitting a low of 3.2 percent on the last day of May. But the rebound has been quick. At FiveThirtyEight, where a slightly different mix of polls are weighted for reliability and adjusted for partisan bias, the Democratic lead is up to a similar 8.5 percent. These are numbers considered consistent with pretty sizable net gains in House seats, and according to many analysts, probably enough to flip control, particularly since history usually shows the party not controlling the White House making gains late in the cycle during midterms.

Similarly, what looked earlier in the year like a steadily climbing Trump job-approval rating seems to have leveled off. According to RealClearPolitics averages, Trump’s job-approval percentage is at 42.8 percent. That’s precisely where he was three months ago, on April 12. At FiveThirtyEight, Trump’s average approval rating is at 42.3 percent, down more than a couple of points from his 44.8 percent posting four months ago on March 12. Instead of looking at an outlier 45 percent job-approval rating from Gallup in mid-June — a historic high — it seems more realistic to look at his current 46 percent rating from Rasmussen, the very pro-Republican survey where he hasn’t hit 50 percent since May.

So how does one explain the most recent trends? It’s hard to say, but for the most part it appears that both the generic congressional- and Trump-approval numbers are reverting to the mean after a brief period of pro-GOP and pro-Trump trends, perhaps because of a combination of less unambiguously robust economic news, abatement of high expectations from the North Korea summit, and all those distressing images from the southern border. Perhaps the numbers will turn around again, but at this point the commonly discussed (among Republicans, anyway) idea that 2018 would turn out to be a good GOP year after all seems implausible.

At the level of individual districts, projections unsurprisingly get cloudier. One trend worth watching was identified earlier this week by the Cook Political Report’s House race wizard David Wasserman:

In the June NBC/WSJ poll, 65 percent of Democratic women and 61 percent of whites with college degrees expressed the highest possible levels of interest in the midterm elections. However, only 43 percent of Latinos and 30 percent of young voters (18 to 29) did.

This explains why so far, the “blue wave” is gathering more strength in professional, upscale suburban districts where women are mobilized against Trump than in young, diverse districts where Democratic base turnout is less reliable.

Since Democrats need gains in both kinds of districts, the national averages could be misleading. But on the other hand, the odds are still in the donkey’s favor:

If the 24 Toss Ups were to split evenly between the parties, Democrats would gain 18 seats, five short of a majority. But that doesn’t take into account that there are 26 GOP-held seats in Lean Republican with strong potential to become Toss Ups, and an additional 28 GOP-held seats in Likely Republican with the potential to become more competitive. In other words, there’s still a lot of upside for Democrats.

After some anxious weeks for Democrats in the spring and early summer, that’s not a bad characterization of the overall landscape in the House with under four months left to go.