Expanding health coverage, reforming our democracy, restoring upward mobility with well-paying jobs, curbing gun violence, and moving to repair our immigration system. 

Oh, yes, and protecting our constitutional republic from President Trump while rooting out corruption.

This should be the agenda of Democrats in the House of Representatives. Already, some pundits are warning that the new majority will “overreach.” But overreach is not the problem for a party that controls only one chamber of Congress.

The bigger threat is underachievement. Democrats will squander their victory—their largest gain in House seats since 1974—if they fail to use their power to show what the alternative to Trumpism looks like. 

Yes, many of their ideas will die in the Senate. But Republicans in that increasingly unrepresentative body should be made to pay a high price for thwarting progress. If the cost proves high enough, some good things might happen before 2020. 

This is not about Democrats going “hard left,” a phrase we’ll hear a lot on Fox News. What unites the staunch progressives and their less-overtly ideological brethren who won many of last week’s contests is a desire to demonstrate that government, used intelligently, can make life better for the vast majority.

Finding common ground across the center-left, one of the political imperatives of the new majority, does not mean least-common-denominator politics. It means agreeing on steps in the right direction: more people with health care, higher wages and family leave; more with an unimpeded right to vote; more feeling safer from violence; more with confidence that our system is not a cesspool.

Democrats are also being counseled against becoming the all-investigations-all-the-time party. But these admonitions assume that the party’s leaders are, well, idiots. It won’t be difficult to use the normal course of House business to hold hearings that expose both the policy failures of the Trump presidency and the corruption he has fostered. Committee chairs should carefully time the inquiries so that scandals don’t push each other aside and thereby fail to penetrate the public consciousness.

There should be a heavy emphasis on how Trump has betrayed his core promises—to stand up for forgotten Americans to whom he has delivered nothing but hateful demagoguery, most recently his evanescent interest in “caravans”; and to drain a swamp he is in fact polluting even more. 

All this would be easier if the rule of law did not face such a dire threat from Trump himself. His almost certainly illegal appointment of the swampy Matthew Whitaker as acting attorney general represents just such a peril. Given the Senate’s sycophancy toward Trump, it falls to the House, the media and lower-court judges to protect us from autocracy. (We’ll learn if the Supreme Court can live up to its constitutional responsibilities.)

It is dangerously false to argue that Democrats must choose between legislating and holding Trump accountable. History gives them no choice but to do all they can to stop Trump from wrecking special counsel Robert Mueller’s inquiry, destroying evidence and politicizing law enforcement. If the president says the price of a decent infrastructure bill is Democratic acquiescence to law breaking, let Trump pay the cost of breaking one of his signature pledges. It’s in his interest to build those roads and bridges.

Remembering what you campaigned on is always a good idea. Democrats have pledged quick action on protecting the insurance of Americans with pre-existing health conditions and enacting a comprehensive democracy reform package with strong provisions on voting rights, campaign-finance reform, gerrymandering and ending the various forms of Trump-era corruption. 

The next step would be expansions of health coverage through a public option or a Medicare buy-in consistent with the views of new members across the spectrum.

Also a priority: strong measures against gun violence. The mass killings continue unabated. Inaction would be immoral. It would also break the commitments so many of the newly elected made.

For the longer term, Democrats need to listen to former Agriculture Secretary Tom Vilsack and writers Alec MacGillis and Michael Tomasky on the imperative of forging a new agenda for rural, small-town and small-city America. Confining opportunity to the large metropolitan areas will deepen national divisions and, by the way, foster long-term Republican control of the Senate.

Over the last century, Democrats held the House without controlling the Senate for only six years, between 1981 and 1987. The novelty of their situation underscores the need for both realism and vision. Combining them isn’t easy. But it’s their only path to seizing the opportunity they’ve been granted. 

(c) 2018, Washington Post Writers Group