Immigration in essence is an issue that hinges on race. White conservatives vote on race. As Michael Tesler, a political scientist at the University of California at Irvine, put it in The Washington Post in November 2016:

Racial attitudes became strongly connected to whether whites identified as Democratic or Republican during Barack Obama’s presidency. That, by itself, meant that racial attitudes would matter a great deal in 2016 — even above the powerful impact of partisanship itself. There is now a stronger partisan divide than ever between racially sympathetic and racially resentful whites. Indeed, the divide is so large it exceeds what was true in 2008 and 2012 — when there was an actual African-American candidate on the ballot.

Republican turnout swamped Democrats in 2016: As my colleague David Leonhardt wrote last year, if liberals voted at the same rate as conservatives, Hillary Clinton would be president.

A June 2017 report issued by the bipartisan Democracy Fund’s Voter Study Group found that a subset of all voters that the organization calls “American preservationists” gave Trump 20 percent of his total vote. It was these voters who comprised “the core Trump constituency that propelled him to victory in the early Republican primaries.” American preservationists, the study group found, “take the most restrictionist approach to immigration — staunchly opposing not just illegal but legal immigration as well.”

In testing racial attitudes, Pew asked voters to choose between “blacks who can’t get ahead in this country are mostly responsible for their condition” and “racial discrimination is the main reason why many black people can’t get ahead these days.” The percentage of Democrats citing discrimination grew from 28 percent in 2010 to 50 percent in 2016 to 64 percent in 2017.

A similar pattern, although less extreme, can be seen in responses to questions on environmental issues. For example, from 2006 to 2014, the percentage of Democrats who believed that there is “solid evidence that the average temperature on earth is getting warmer,” fluctuated from the mid to high 70s. In 2017, it shot up to 92 percent.

Celinda Lake, a Democratic pollster, sees the trends among Democratic voters as a clear plus, with little downside:

There has been a tremendous shift in the public to progressive positions and awareness — on marijuana, on marriage equality, on calling out racism, on #MeToo, on support for comprehensive sex education and women’s reproductive health issues. Democrats are both leading the way and catching up. Millennials are the future and they are totally in support of these positions.

Jonathan Cowan, president of Third Way, a centrist Democratic think tank, is more ambivalent.

On the plus side, he wrote in an email,

this shorter-term trend clearly comports with the multi-decade trend in which both the country at large and the Democratic Party itself have become increasingly more open-minded, pluralistic and progressive on a range of social issues, including racial justice, immigration and women’s rights.

Cowan then shifted to what he called “the rest of the story”:

Not all of the country is moving at the same pace. Donald Trump won a national election playing a brand of racial politics not seen in this country since George Wallace. So while Democrats fight for progress and justice on racial issues, we cannot be dismissive or scornful of voters who do not share precisely the same views or beliefs, but who nonetheless want an alternative to the hard-core misogyny, nativism and racism of Trump.

Third Way analyzed all 435 House districts in anticipation of the 2018 election and reached the conclusion that the key fights will be in districts that require appeals to swing voters to win.

The study found that 168 districts are virtually certain to elect Democrats, who currently hold 165 of these seats. On average, these districts are 44 percent white and 56 minority.