Some of this is now out-dated, owing to continuing counts of ballots and recounts.
“Analyzing 417 House races that featured at least two candidates on the ballot, the AP determined that Democrats earned more than 51.4 million votes in competitive House races nationwide, or 52 percent, compared to 47.2 million votes cast, or 48 percent, for Republicans.”
NB: Of 98.6 million votes cast, Republicans won about 47.8 percent of the 2016 vote. Democrats won about 52 percent of the vote.
NB: The Democrats margin of victory was 4.2 million votes. In the “American presidential election held on November 8, 2016,… Republican Donald Trump lost the popular vote to Democrat Hillary Clinton by more than 2.8 million votes. NB: So two years of Trump government energized Democrats more than did Hillary Clinton’s campaign. No surprise.
NB: Will this be enough to win the White House in 2020? Basically (back of the envelope), it looks like Republicans pulled 74.6 percent of their 2016 turnout, while Democrats pulled 78 percent of their 2016 turnout. Motivated by the Kavanaugh shenanigans, Republicans turned out much more than one might have expected. Motivated by Trump-vulsion, Democrats turned out as one might have expected.
“According to the latest data, Democrats won the House popular vote by about seven percentage points in Tuesday night’s midterms.” [NB: that works out to be something like 53 percent to 46 percent.] Furthermore, “They picked up 29 Republican-held seats in the House, while losing two of their own incumbents, resulting in a net gain of 27 seats.”
“From 1918 to 2016, the president’s party lost an average of 29 seats in midterm elections. In the 20 percent of elections where the president lost the most seats—which Ballotpedia defined as wave elections—his party lost at least 48 seats.” “In the 2010 midterms, by contrast, Republicans stormed into control of the House with a haul of 63 seats.”
“Each of America’s 50 states elects two senators, regardless of population, and only a third of the country’s Senate seats are voted on each election cycle.” According to David Golove, a professor at the New York University School of Law, “That’s a radically undemocratic principle, and it gives rise to what we see, which is that the minority populations are going to have a disproportionate impact in the United States. That tends to mean conservatives have a disproportionate influence over the Senate.”
NB: OK, but his argument is with James Madison, not me. Wear a cup.
The country is divided 52-48 percent. A purely normal (see above) “blue wave” should not disguise this reality.
Still, if the Democrats have a good candidate and can sustain their “get out the vote” effort, they have a fair chance of re-capturing the White House in 2020.
Of course, we’ll have to take what comes with getting Trump out of the White House.
 Donald Trump: 62,984,828; Hillary Clinton: 65,853,514.
 Aye, there’s the rub. Could Corey Booker or Kamala Harris or Elizabeth Warren or Joe Biden mount a credible candidacy? More likely, JMO, Hillary Clinton will “offer to serve” when the midgets flame out.