Yet if Democrats win the presidency—and even both houses of Congress—their difficulties will burgeon the day Trump leaves office. Not only must they hold their own coalition together as they contend with the coronavirus and the economic crisis that it created, but they will face fierce opposition from the voters who support Trump despite everything. Far from being chastened into moderating the GOP’s rhetoric and cooperating with a new administration, the remaining elements of a vanquished Republican Party will likely become more extreme. It’s happened before…

California Republicans were the first to act on the economic and cultural fears raised by immigration. As the Latino population grew, state Republicans put Proposition 187 on the ballot in 1994. It barred undocumented immigrants from attending public schools or using public hospitals and required cooperation with federal immigration officials. Its passage had a huge negative impact on Black and Latino support for Republicans, but more important, it led to immigration crowding out other issues. Republicans became a predominantly white, socially conservative, anti-immigration party with little interest in education, the environment, and other issues of interest to moderate voters. Before Proposition 187, Democrats and Republicans were both competitive in races for president and governor and evenly split the state’s seats in the House of Representatives. But in 2010, Democrats won every statewide office.

What’s instructive is how Republican leaders reacted as their party fell further and further behind. Each year, they fielded fewer moderate candidates; in the 2018 midterm, a Democratic-wave election, California Republicans were annihilated. The pro-Trump-supported gubernatorial candidate got only 38 percent of the vote. In Orange County, once Ronald Reagan’s suburban heartland, every GOP member of Congress lost. Republicans held on to only seven congressional seats in the whole state of California.