The Washington Post has the tally of U.S. House of Representatives election results in 2020 at 222 Democrats, 205 Republicans, and 8 races yet to be called. Democrats will control of House where a majority is 218 seats.
If one is a little less cautious than the Washington Post in calling races, the real tally so far (including the runoff that the Republican is sure to win in the GOP tally) is 222 Democrats, 211 Republicans and 2 races too close to call (voting counting has gone slowly in New York and Iowa). The Democrats can afford to have just 4-6 defectors on any given vote in the House (i.e. they need 97%-98% party loyalty on partisan issues).
Democrats had 235 seats immediately after the 2018 midterm elections and the special election in North Carolina (won by a Republican) when that election was invalidated due to election fraud.
So, Democrats have lost at least 11 net seats so far, and could ultimately lose as many as 13 net seats.
Roughly one in twenty seats held won Democrats in 2018 have flipped to the Republicans. Republicans flipped two seats in special elections to fill vacancies between 2018 and 2020. Republicans have flipped twelve to fourteen Democratic seats in the 2020 election, including two rated as "Safe Democratic" seats. Democrats have flipped just three Republican seats.
This is pretty horrible, given the circumstances.
Voter turnout, which tends to favor Democrats was the highest it has been since 1900. Democrats performed better in campaign spending relative to Republicans in 2020 than in any other election in recent history. And, while there is no doubt that the number of seats that Democrats won was reduced by gerrymandering, this can't be blamed for the decline in the number of seats won in the 2020 election relative to the 2018 election which was conducted using them small Congressional district boundaries. And, every incumbent running for Congress in 2020 won a race in the same district just two years ago.
Also, there was ever reason to expect that Democrats would benefit from coattails in down ticket house races.
Democrat Joe Biden won the Presidential election with 306-232 electoral votes and a roughly 3 percentage point lead in the popular vote (although he underperformed polling averages by about 4 percentage points, on average). Democrats will be hard pressed to secure the 50 seats in the U.S. Senate needed to control the Senate since they need to win two uphill runoff elections in Georgia on January 5, 2021 to do so, but they at least picked up three Republican seats while losing just one Democratic seat (in Alabama where their previous special election win was a fluke made possible by Roy Moore, the truly awful Republican nominee in that election).
Where did the Democrats stumble?
Democrats lost 1% of their "safe Democratic" seats (as rated by Cook's Political Report) and about half (± one seat) of the "Vulnerable Democrat" seats.
Five of the seats (three in California and two in Southern Florida) seem to reflect GOP strength in 2020 with certain Hispanic communities.
Six plus the two uncalled seats (in Iowa, Minnesota, New York, Oklahoma, South Carolina and Utah) seem to reflect a return or possible return to a "natural" GOP lean from a blue wave in 2018 spurred by opposition to Trump.
One (in New Mexico) seems to involve a bit of both of these factors.
Democrats won just 8% of the "Vulnerable Republican" seats and none of the "Safe Republican" seats. Each was an urban-suburban district in the South (one in Georgia and two in North Carolina) that was about 20% black.
A detailed district by district breakdown supporting the six races that I have called that the Washington Post has not yet called, is below the fold.
Cook's Political Report sorted the races into four categories going into the election: Safe Democrat (209), Vulnerable Democrat (24), Vulnerable Republican (37), and Safe Republican (165).
Two Democrats in "Safe Democrat" seats lost their races: CA-39 (49.4% to 50.6%) and FL-27 (48.6% to 51.4%). This is still a 99% win rate for "safe Democratic" seats.
Of the "Vulnerable Democrat" seats, 11 have been called for Democrats and 8 have been called for Republicans (CA-48, FL-26, IA-1, MN-7, NM-2, OK-5, SC-1, and UT-4). Four races have not yet been called; Republicans are leading in three of them and one is a virtual tie.
Republicans will probably win at least two of them: CA-21 (49.4%-50.6% with more than 99% of the vote counted) and NY-11 (42.1%-58.9% with 85% of the vote counted).
Democrats lost CA-21 (open seat, Fresno, 71% Hispanic), CA-39 (safe, suburban LA, 34% white, 33% Hispanic, 29% Asian), CA-48 (Laguna Beach, 59% white, 20% Hispanic, 18% Asian), FL-26 (Miami, 72% Hispanic), FL-27 (safe, suburban Miami, 72% Hispanic), IA-1 (Cedar Rapids, 88% white), MN-7 (Western MN, 88% white, second most GOP leaning district in U.S. represented by a Democrat), NM-2 (Southern NM including Las Cruces, 27% Hispanic, 6% Native American), NY-11 (conservative district with a first term Democratic incumbent, Staten Island, 73% white), OK-5 (first term Democratic incumbent, Oklahoma City, 69% white), SC-1 (first term Democratic incumbent, Charleston, 21% black) and UT-4 (most GOP district in U.S. represented by a Democrat, Salt Lake City, 84% white).
Either candidate could genuinely win both NY-22 (47.4%-50.4% with 92% of the vote counted) and IA-2 (50.0%-50.0% with 89% of the vote counted), because in this election cycle, late counted votes have tended to favor Democrats. These seats are IA-2 (open seat, Davenport, 85% white) and NY-22 (Utica, 90% white).
All but one of the "Safe Republican" seats have been called for a Republican. The only exception is LA-5 where the leading Republican in the race got 33.1% of the vote, while the leading Democrat got 16.4% of the vote, causing the race not preceded by a primary to go to a runoff election, in which Republicans, who split the first round vote, will unite around the Republican plurality winner and hold the seat for the Republicans.
Of the "Vulnerable Republican" seats, 31 have been called for Republicans, 3 have been called for Democrats (GA-7, NC-2 and NC-6). Republicans are leading in all three of the races that have not been called and will probably win all three of them: CA-25 (49.9%-50.1% with more than 99% of the vote counted), NY-2 (42.6%-56.4% with 83% of the vote counted), and NY-24 (38.9%-57.4% with 92% of the vote counted). The NY-2 race was conceded two days ago by the Democrat in the race.
Republicans lost GA-7 (closest race in the U.S. in 2018, suburban Atlanta, 21% black), NC-2 (open seat, Raleigh, 20% black) and NC-6 (open seat, Greensboro, 20% black) North Carolina was forced by the Courts to redraw its districts in advance of the 2016 elections, so this was only the second election held in the two North Carolina districts picked up as they are currently drawn.