From one direction, Trump faces intense antipathy among young people and minority voters and unusually broad resistance among college-educated white voters, especially women. That threatens Republicans with widespread losses in well-educated, often racially diverse, suburbs in major metropolitan areas around the country, as well as the possible loss of Senate seats in the diverse and growing Southwest states of Nevada, Arizona and possibly (though less likely) Texas.

On the other side, Trump retains strong support among evangelical, rural and non-college-educated white voters, including women. Trump has energized these voters with a campaign closing argument that appeals to white racial fears and resentments more overtly than any national political figure since George Wallace in the late 1960s.

Trump's efforts are aimed primarily at reinforcing Republican opportunities to oust incumbent Democratic senators in several older, preponderantly white interior states that voted for him in 2016. The high energy among Trump's base is also sustaining long-shot Republican hopes of narrowly holding the House -- or at least minimizing any Democratic majority -- by maintaining the GOP's control of most exurban and blue-collar seats outside the major metropolitan areas.

The result could be a bifurcated midterm result that simultaneously repudiates Trump while providing him some reaffirmation. While most debate has focused on whether a backlash to Trump will spur a "wave" of Democratic gains, today's election seems more likely to solidify and even deepen the stark geographic and demographic divisions that marked Trump's election in 2016. The prospect that turnout will vastly exceed the level in 2014, the most recent midterm election, by perhaps 20 million votes or more, underscores the sense that this campaign may mark a new peak in the partitioning of American society between two political coalitions separated above all by whether they welcome or fear the profound demographic, cultural and economic changes remaking US life.

On balance, Democrats appear positioned to secure the best results. Beyond the battle for Congress, Democrats are on track for significant gains in governors' races , including in several of the key Rust Belt battlegrounds that keyed Trump's victory. And last-minute polls suggest that if there are surprises in the House and Senate contests, it is more likely to be Democrats prevailing in Trump's terrain than Republicans showing unexpected strength in culturally liberal suburban areas. But the GOP's continued strength among working class and non-urban white voters could allow it to gain Senate seats, and, though much less likely, narrowly defend its House majority.

Coalitions of restoration and transformation

The election will provide a vivid snapshot of the ongoing polarization of the electorate that Trump has deepened and solidified. Final polling at the national and state level shows Democrats running extremely well among what I've called their "coalition of transformation": minorities, millennials and college-educated white voters, especially, but not exclusively, women. All of these groups register intense antipathy for Trump in polls: 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, according to figures provided by CNN polling director Jennifer Agiesta. Just over half of college-educated white men also preferred Democrats in the survey. That represents a sharp swing from their usual congressional voting behavior: 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.

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%) but it is still enough to provide Republicans big leads over Democrats with those voters in these surveys. 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 in the CNN survey, albeit by a much slimmer 53% to 45%; that would be the best showing for Democrats in congressional races since 2006, but might still leave them scrambling to build a winning coalition in House and Senate races dominated by working-class whites.

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The Democratic strength with the "coalition of transformation" positions the party for significant gains in suburban districts outside the South where large numbers of ordinarily Republican-leaning college-educated voters dislike or even disdain Trump. This recoil virtually guarantees substantial Republican losses in well-educated House districts the party now holds in New Jersey, Philadelphia, Northern Virginia and Miami in the East; Chicago, Detroit, Kansas City and Minneapolis in the Midwest; and Denver, Tucson, Orange County, California, and probably Seattle in the West. That geography underscores the irony that House Republicans today face their greatest risk in the places that are doing best in the economy -- but where large numbers of voters reject Trump's values and behavior.

For Republicans to have any chance of preserving their House majority -- or even to hold down a potential Democratic majority to a level that maintains a reasonable chance of the GOP recapturing control in 2020 -- the party needs to minimize its losses beyond those places. The reverse is true too: Unless Democrats can expand beyond the epicenter of Republican vulnerability in the white-collar suburbs outside the South (especially the Republican-held districts that voted for Hillary Clinton over Trump in 2016) they will be operating with little margin for error in their drive to recapture 23 seats and the House majority.

Republicans need a firewall

That means one key question is whether Republicans can build a firewall around two other groups of districts. One is white-collar suburbs in the South. Traditionally Southern suburbanites have embraced much more conservative positions (especially on social issues) than their counterparts in other regions. But this year Democrats are mounting serious challenges for suburban seats near Raleigh, North Carolina; Atlanta; Houston; Dallas; Tampa, Florida; Charleston, South Carolina; and Richmond, Virginia. Republicans can't afford to lose many of those.

Likewise, the GOP can't afford many losses in blue-collar and exurban districts outside the South that are dominated by the key groups in the "coalition of restoration." Top-tier Democratic targets fitting that description include seats in Maine, upstate New York, northeastern Iowa and central and northwestern Pennsylvania that have drawn increasing attention in the campaign's final turn. One especially revealing group of seats may be those that sit at the intersection of the parties' competing coalitions: places like the districts near Pittsburgh; Seattle; Des Moines, Iowa; Lexington, Kentucky; and Charlotte, North Carolina, that combine suburban with rural populations. The results in those seats will measure the relative enthusiasm of the suburban coalition mobilizing against Trump and the small-town and rural coalition rallying to his defense.

Trump is dividing the country but solidifying his base

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Trump's embrace of such a racially polarizing final message can be interpreted as a form of triage in the House. Almost all Republican consultants agree he is compounding the problems for the GOP incumbents trying to survive in the suburban seats at greatest risk. But he may also be fortifying Republican defenses in the blue-collar, exurban and small-town seats beyond that inner circle of vulnerability. Put another way, Trump's divisive close may be reducing the odds that Democrats win 45 seats in the House -- but at the price of increasing the odds that they win the 23 they need to recapture the majority.

Trump's open appeals to racial anxieties and xenophobia are intended above all to boost Republican prospects against nine Democratic senators seeking re-election in preponderantly white, heavily blue-collar and older interior states that he carried in 2016. (A 10th Democratic senator, Bill Nelson, is seeking re-election in Florida, a much more diverse state that Trump also carried.)

Four of those states across the industrial Rust Belt have essentially moved off the board for Republicans, with Democratic incumbent Sens. Sherrod Brown in Ohio, Tammy Baldwin in Wisconsin, Debbie Stabenow in Michigan and Bob Casey in Pennsylvania all holding commanding leads. (Democrats also have an opportunity to win the governorship in each of those states, as well as Iowa.)

But Republicans are considered solid favorites to beat Democratic Sen. Heidi Heitkamp in North Dakota and have mounted strong challenges to Democratic Sens. Claire McCaskill in Missouri and Joe Donnelly in Indiana, though late polls give each Democrat reasons for optimism. Sen. Joe Manchin in West Virginia appears the best positioned of these remaining Trump-state Democrats to survive, but Sen. Jon Tester in Montana remains a wild card amid conflicting polls in the campaign's final days.

In both the House and Senate, the strong emotions surrounding Trump appear likely to accelerate the transformation of congressional races into quasi-parliamentary contests in which individual assessments of the two candidates are overshadowed by broader judgments about the President and the two parties.

Since the early 1990s, the relationship has grown stronger between how voters grade the sitting president and whether they support his party's candidates in House races. But 2018 may push that trajectory to a new peak. In the past three midterms (2006, 2010 and 2014) between 82% and 84% of voters who disapproved of the president's performance voted against his party's candidates in House races, while 84% to 87% of those who approved voted for them, exit polls found. In the new CNN survey, 91% of Trump approvers said they planned to vote Republican while 92% of disapprovers said they intended to vote Democratic; in the ABC/WP survey the numbers were just under 9 in 10.

Red states and blue states

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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. Still, the number of House districts that "split their ticket" between the presidential and congressional votes will likely remain very low by historic standards, and could even shrink further.

The Senate could see the same pattern. Already it's grown much more difficult for senators to win in states that usually vote the other way in presidential elections. 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:

13 states have voted Republican in all seven presidential elections since 1992. Democrats hold just two of their 26 Senate seats and are at high risk of losing one of them, Heitkamp's seat in North Dakota. (They could replace that seat if Beto O'Rourke upsets Sen. Ted Cruz in Texas, which has also voted Republican in each of the past seven presidential races.)

Democrats hold just two of their 26 Senate seats and are at high risk of losing one of them, Heitkamp's seat in North Dakota. (They could replace that seat if Beto O'Rourke upsets Sen. Ted Cruz in Texas, which has also voted Republican in each of the past seven presidential races.) 5 states have voted Republican in six of the past seven presidential elections. Democrats hold just two of their 10 Senate seats, and those two, Tester and Donnelly, are at high risk (though Kyrsten Sinema in Arizona is bidding to become the third).

Democrats hold just two of their 10 Senate seats, and those two, Tester and Donnelly, are at high risk (though Kyrsten Sinema in Arizona is bidding to become the third). 6 states have voted Republican in five of the past seven presidential elections. Democrats hold only two of their 12 seats. Manchin and especially McCaskill both face tough races. (Phil Bredesen in Tennessee, which has also voted Republican five of seven, could replace one of them.)

Democrats hold only two of their 12 seats. Manchin and especially McCaskill both face tough races. (Phil Bredesen in Tennessee, which has also voted Republican five of seven, could replace one of them.) 2 states have voted Republican in four of the past seven elections. Democrats hold three of their four Senate seats, but Nelson is in a tough race to hold one of those in Florida.

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.

All of these dynamics point to the same bracing conclusion: 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.

The result is that on Wednesday morning, the distance and discord between the coalitions of transformation and restoration may be more vividly apparent than ever. What's less clear is whether America can find any political common ground, or even maintain its social cohesion, as that fault line grows more jagged and volatile.