Republicans hold a huge intrinsic advantage because they dominated the redistricting process after the 2010 elections in many states. Voter self-sorting further contributes to the Democrats’ problems. Democrats will almost certainly win more votes for Congress on Tuesday — generic ballot polls put them ahead by margins of 8 or 9 percentage points, larger than the margins in the 1994 Republican wave or Obama’s landslide victory over John McCain in 2008. But Democrats would have to win the popular vote by somewhere on the order of 5 to 7 percentage points, according to the various versions of our model, to actually win the majority of House seats.- Nate Silver at 538.
Demographic divides are very deep this year.
In the latest CNN survey, conducted by SSRS, Trump's approval rating stood at just 22% among minorities, 32% among young adults and 37% among college-educated whites. That bleak assessment keyed a Democratic advantage in the congressional ballot of 49 percentage points among minorities, 26 points among voters ages 18 to 29 and 22 points among college-educated whites, according to the poll.
Over two-thirds of college-educated white women, an unprecedented number, said they planned to vote Democratic for Congress. . . . Just over half of college-educated white men also preferred Democrats . . . . Democrats haven't won even 40% percent of college-educated white men in any congressional election since 2008, according to exit polls.
But Trump retains substantial loyalty among the competing Republican "coalition of restoration" revolving around older, evangelical, rural and blue-collar whites -- the sorts of voters who dominate the mostly small-town and red-state sites where he has held nonstop rallies in recent days.
From CNN.In both the CNN survey, and an ABC/Washington Post survey released Sunday, Trump's approval rating among non-college whites stood at 56%. That represents an erosion from his 2016 vote among them, according to exit polls (67%). . . . The CNN poll shows non-college whites preferring Republicans for Congress by a 20-percentage-point margin, while the NBC/WSJ survey also released Sunday showed them with a 24-point advantage and the ABC/WP put their lead at 25 points.In a mirror image to the well-educated women, nearly two-thirds of white men without a college education said they planned to vote Republican in the CNN poll. Non-college white women also preferred Republicans . . . by a much slimmer 53% to 45%; that would be the best showing for Democrats in congressional races since 2006[.]
Geographic divides are also very deep and realignment continues to run its course.
By historic standards, the number of representatives in districts that voted for the other party's presidential candidates is already very low: Just 25 Republicans are in districts that preferred Clinton and only 12 Democrats hold seats in districts that backed Trump. At least two-thirds of the Republicans in Clinton districts are in serious jeopardy today, which means that the number of GOP members from such seats could fall into single digits after the election. Republicans, in turn, have at least some chance of dislodging about one-third of the Democrats in Trump districts, though Democrats today also have opportunities to offset that by capturing over a dozen districts that Trump won. . . .
Sen. Susan Collins of Maine, who faces re-election in 2020, for instance, is the only Republican left among the 30 senators elected in the 15 states that have voted Democratic in every presidential election since 1992.
This election could further cull the already diminished ranks of Democratic senators in red-leaning terrain:
In all, Republicans already hold 43 of the 52 Senate seats in the 26 states they have carried in at least four of the seven presidential elections since 1992. If Democrats have a bad night, Republicans could emerge with more than 45 of those seats.
By contrast, with their Rust Belt recovery, Democrats do not appear at serious risk of losing any the 40 Senate seats they now hold in the 24 states they have won in at least four of the past seven presidential elections. They have a good chance even of adding one, in Nevada, where Democratic Rep. Jacky Rosen is pressing Republican Sen. Dean Heller. . . .
This election is likely to intensify the realignment of the nation into two distinct blocks with inimical visions not only of Trump's belligerent presidency but also of the underlying social, racial and economic changes remaking American life.
Across the country, Democrats appear on track to consolidate their control of House seats in metropolitan areas that are more diverse, younger, secular and connected to the information age and global economy. (Only the South might resist that pattern.) But they may do little to dent the Republican dominance in non-metro areas that are predominantly white, older, heavily Christian and grounded in traditional industries of manufacturing, energy and agriculture. (The Midwest offers Democrats the best chances to make such inroads.) In the Senate, Democrats could gain ground in younger diverse Sun Belt states (Nevada and/or Arizona, conceivably Texas) and simultaneously lose ground in older, mostly white interior states (North Dakota and the others).
In both the House and Senate, each party's caucus may be tilted even more than it is today toward one side of this divide.From CNN.
Political identity is stable and unlikely to be shifted except by mass migrations such as the Mormon migration west and the Okie migration recounted in "The Grapes of Wrath" during the 1930s dustbowl.
From here.In this paper, we show that the migrations of millions of Okies from the central plains to California has a demonstrable effect on political outcomes to this day, even after accounting for other relevant geographic and demographic factors. After demonstrating this pattern at the electoral level, we leverage a decade's worth of survey data and show that Hispanics living in areas with large Okie migrations in the 1930s are much more likely to have conservative social values and, importantly, to vote and identify as Republicans. Put together, these results suggest that the historical legacies of migration can have a strong and sustained impact even after nearly a century after the fact.