There is little question that President Trump and the GOP will lose this election. With Mr. Trump’s approval rating hitting a historic low for an incumbent president before the midterms, Republicans will cede control of the House and likely the Senate. What is still far from clear is whether Democrats will win. That question won’t be answered on Nov. 3 but over the next two years.

The top story from the 2026 cycle will be the electoral opening Democrats seized—and will have to maintain. Most important, the McCain-Romney Republicans, who are politically homeless, need to be welcomed into Democrats’ governing and electoral coalition. More than 25% of self-described “non-MAGA Republicans” would prefer Democratic control of the next Congress. That is crucial because as in 1991 and 2007—the years before Bill Clinton and Barack Obama won the White House—how Democrats govern in 2027 will determine what happens in 2028 and beyond.

Nearly a half-century ago, we saw this story play out in reverse. Working-class members of the New Deal coalition—the Reagan Democrats Stan Greenberg famously identified in his 1985 study of Macomb County, Mich.—walked away from the Democratic Party. After the 1980 election, Reagan’s strategists worked to solidify their loyalty to the GOP, and the realignment stuck. By contrast, Mr. Trump had a historic opening with Hispanic voters after the 2024 election but squandered it with his reckless immigration raids.

Millions of McCain-Romney voters are redefining their political identities, and they will be most responsible for Democratic gains in November. These voters don’t want to be associated with MAGA, and they see themselves as free agents. The question for Democrats is whether we’re willing to give them a permanent home.

Americans are angry about grocery and gasoline prices. But a recent Fox News poll indicates that corruption is a more salient issue for voters than affordability. This is the opening we need to draw non-MAGA Republicans into our camp.

Ex-Republicans are already running under the Democratic label in crucial races this cycle. David Jolly, a former Republican congressman, may become the first Democrat elected governor of Florida in 32 years. Mr. Jolly has run on an anticorruption message and argues his GOP opponent, Rep. Byron Donalds, “will sell you out for a buck.”Adam Hamilton, a Methodist pastor and former Republican, is attacking incumbent GOP Sen. Roger Marshall as a Trump “yes man” mired in his own corruption.

If Mr. Hamilton pulls out a victory, he will be the first Kansas Democrat elected to the Senate since 1932. Gov. Katie Hobbs, the Arizona Democrat seeking re-election, is so determined to move past Trump-style vitriol that she selected a former mayor of Mesa who switched from Republican to independent as her running mate.

These examples should teach Democrats two things. First, once many Trump voters realized that his promise to “drain the swamp” was mere rhetoric, they soured on MAGA. Second, by embracing a “What’s the Matter with Kansas?” perspective, far-left progressives spent far too much time disparaging Americans who believed the president’s rhetoric. Rather than vilifying those whose support we need, Democrats should be inviting them into our coalition. Voters willing to give Democrats a second look need convincing to trust us.

That should shape our agenda over the next two years. The new Democratic Congress should pursue oversight of the Trump administration, which has been sorely lacking. But venomous hearings won’t achieve the substantive progress Americans want, unless the drama leads to real change. To that end, rather than impeaching Mr. Trump, Democrats should champion an ethics-reform package designed to rebuild the public trust that Washington has spent decades squandering.

This legislation should include the following four proposals: First, ban stock trading for elected and appointed officials in all three branches. Second, prohibit their participation in prediction markets. Third, require government officials who have a net worth of more than $1 million to put their assets in a blind trust while serving. Finally, to prevent the foreign interference the Founding Fathers worried about, ban all foreign gifts and investments to public officials while serving and for two years after they leave office. This would have precluded a firm linked to the United Arab Emirates from investing $500 million in the Trump family’s crypto enterprise.

Democrats should also address the cost of living. We should immediately raise the federal minimum wage, the first hike in nearly two decades. Next, we should reduce the tariffs that have proved so counterproductive. By making government deliver again, we’ll come out ahead politically and, more important, substantively.

Our overriding goal should be to ensure that this election is more transformational, à la 1980, than transactional. The result won’t be decided in blue-to-blue districts—that is, places where Democratic Socialists of America candidates have ousted Democratic incumbents. We should focus instead on the red-to-blue districts that will determine the size of our majority. These are places full of independents who feel cheated and McCain-Romney Republicans who feel politically abandoned.

The activists who reside in blue bubbles are sure to interpret the election results as vindication. But the party’s ascent won’t be born of some newfound enthusiasm for far-left policies such as defunding the police or offering free healthcare to illegal immigrants.

The American people are tired of the invective they see out of Washington. They don’t want a Democratic version of Mr. Trump’s Hunger Games. By embracing the strategies that sent Messrs. Clinton and Obama to the White House, Democrats can solidify a winning 2026 coalition that is eager for change rather than more partisan mudslinging.

Mr. Emanuel, a Democrat, served as a U.S. representative from Illinois (2003-09), White House chief of staff (2009-10), mayor of Chicago (2011-19) and ambassador to Japan (2022-25).

[video] WSJ Opinion: Matthew Continetti in Conversation with Rahm Emanuel