The Democratic advantage in congressional generic ballot polls has been shrinking

For the past few months, Democrats have been riding high on a generic ballot advantage that shows them about 7 or 8 percentage points ahead of the Republicans in the 2018 midterms — an edge that signifies a potentially historic wave election.

But Democrats just got their first sign of trouble.

A new ABC News/Washington Post poll released Monday shows that Democrats have just a 4-point advantage over their GOP counterparts; 47 percent of registered voters polled said they prefer the Democratic candidate in their individual district, while 43 percent of those polled favor the Republican candidate.

However, when ABC and the Washington Post posed the same question to a wider group of adults of voting age (not just registered voters), the Democratic spread was better — a 10-point margin, with 50 percent of adults saying they preferred the Democratic candidate and 40 percent preferring the Republican.

The larger picture is that the very wide advantage Democrats had this winter is shrinking. In December, Democrats had a 13-point lead on the generic ballot, and that has decreased significantly.

Of course, the ballot has fluctuated all year and will continue to do so. The generic ballot spread still has Democrats up about 6 points, according to RealClearPolitics.

Part of the reason Republican numbers are gradually improving is that President Donald Trump’s approval numbers are also improving. The Post/ABC poll found 40 percent of registered voters approve of Trump, a slight uptick from 36 percent in January. That 40 percent approval rating is Trump’s highest level of support since last April, but the president continues to have a record disapproval rating.

There’s also good news for the GOP in making gains among white voters, who said they prefer Republicans by a 14-point margin over Democrats, up from 5 points in January, according to the poll. Among white voters without college degrees, Republicans lead by 60 percent to 31 percent, slightly larger than their margin three months ago.

Bolstered by special election wins over the past few months, a Democratic wave has gone from a hope to the conventional wisdom. But there are still a number of speed bumps between now and November that Vox’s Dylan Scott outlined recently. The economy is good; Democrats could have something go wrong with some candidates in individual districts; and (especially with Trump as president) there could be a chaotic variable that changes the midterms — think a terrorist attack, natural disaster, or war.

As Scott wrote:

The conventional wisdom is solidifying that Democrats — buoyed by an unpopular President Donald Trump, an energized Democratic base, ample opportunities for pickups, and the historical rule that voters punish the party in the White House — will win the 20 or so seats they need to flip the House and maybe even get the Senate.

Of course, it’s not in the bag: A lot can happen between now and November, never mind that Senate Democrats are at an extreme disadvantage, that gerrymandering can curb the generic ballot by a lot, meaning there are plenty of R+whatever districts.

In other words, it’s far from over.