Now that House Democrats are focusing on what they will try to achieve when they take control in January, I offered some serious if unsolicited advice at New York:

After a good election result, the conventions of American politics dictates that the winners boast of a popular mandate to do whatever it is they want to do. And if said election delivers less than total power, it’s customary to pledge a robust effort to reach across the aisle to the other party and get things done in the national interest.

You can see both of these conventions reflected in a letter that 46 of the 66 newly elected House Democrats sent to their leadership this week. They claim “a responsibility and mandate for change in the U.S. Congress,” and profess “the importance of addressing concerns that cross party lines.” In reality, of course, bipartisan legislation has become an endangered species, and the remaining Republican minority in the House is more obdurately conservative and partisan than ever. And there isn’t going to be a lot of “change” legislated in partnership with Donald Trump and a Republican-controlled Senate.

Still, these politicians fresh from the campaign trail are on fire to keep talking about “the cost of health care and prescription drugs, our crumbling infrastructure, immigration, gun safety, the environment, and criminal justice reform,” as the letter says. But given partisan realities, the question remains: to what purpose, exactly?

Roll Call’s veteran observer Walter Shapiro raises this question bluntly in terms of the agenda of House Democrats this next year:

“In truth, the only legislative power the House Democrats will have in 2019 is the ability to say ‘no.’

“With a comfortable House majority, the Democrats can veto the further dismantling of the Affordable Care Act, the construction of Donald Trump’s cherished border wall and the new trade treaty to replace NAFTA. But unless Mitch McConnell has a conversion experience rivaling St. Augustine’s, no House-initiated legislation will ever make it to the Senate floor.

“Yet it is easy to envision the House Democrats, goaded by their newer members, spending months arguing over the nuances of a single-payer health plan and wrestling with legislation to overhaul immigration enforcement. Against the backdrop of dire warnings about the acceleration of global warming, far-reaching environmental legislation is likely to be approved by the new House.”

So any progressive legislating the House does will be essentially a matter of “messaging,” or to put it less charitably, agitating the air while awaiting the power to do anything about it. Shapiro acknowledges that this isn’t necessarily a waste of time; policy debates Democrats have now in the wilderness may bear fruit if their party recaptures the White House (and particularly if it gains a trifecta) in 2020. But it’s still a bit of a shadow show. And ultimately, what will likely define the Democratic Party more than anything that happens in Congress will be the policy positions, agenda, and message of the person Democrats nominate for president in 2020. If there’s some “struggle for the soul of the party” on tap, it will take place in Iowa or South Carolina or California, not in the U.S. House of Representatives.

Complicating the picture is that the House will have the power to investigate Donald Trump and his satraps. Yet a lot of Democrats ran campaigns that underplayed or even ignored the Trump circus, and many of the younger members won’t be on the committees where investigations of the president and his administration play out.

So how should the House Democratic leadership deal with the pent-up Democratic desire to do something now that at least one venue is within their control?

Maybe they should take a long look at how Republicans managed their time in purgatory, from the reconquest of the House in 2010 until their achievement of the trifecta in 2016. Unlike today’s Democrats, they did have some opportunities for bipartisanship; President Obama negotiated with the opposition on items big and small far more often than President Trump has done. They did pass a lot of “messaging” legislation they knew the Senate (before 2014) or Obama would kill, but they certainly had no inhibitions about investigating every real and imaginary sparrow that fell to the ground as a result of Obama’s policies.

Most notably, beginning in 2011 Republicans in both Houses signed onto a series of budget proposals — collectively known as the Ryan Budget, in honor of their principal designer, the House Budget Committee chairman and then Speaker — that purported to represent the domestic policy agenda the party would pursue when it gained real power. And in late 2015, holding power in both chambers, they even passed what they advertised as a “trial run” for a huge budget-reconciliation bill that would repeal Obamacare, defund Planned Parenthood, block-grant Medicaid, and begin reshaping the federal government along lines conservative ideologues had promoted for decades. This was the ultimate use of legislation for “messaging:” Here’s exactly what we’ll do as soon as we have the power.

There’s no particular evidence that this sort of exercise helped Republicans win elections from 2012 through 2016, though it probably pleased a lot of conservative advocacy groups and donors. And whatever his ultimate intentions, when Donald Trump was elected president in 2016, given the GOP the long-awaited trifecta, it was not the result of a campaign waged on behalf of the Ryan Budget.

Given Trump’s indifference to conservative ideology, it’s a small miracle that something like the Ryan Budget emerged in 2017 as the united GOP’s first legislative priority. But as we now know, not everyone who voted for the trial run in 2015 voted for the big package of legislation known as Obamacare repeal when push came to shove, and Trump caused constant problems as well with his varying whims on the bill. Now Republicans have lost their trifecta, with Obamacare, Medicaid, and Planned Parenthood funding (among other GOP targets) still intact. And to the extent that they have an agenda going forward, it is lashed to the wavering mast of Trumpism, and whatever follows it. All that show-and-tell about their agenda was mostly a waste of time.

House Democrats should probably learn from their opponents’ experience, and spend less time rehearsing the tasks they will inherit with power, and more time making sure they arrive there in 2020 with the right kind of presidential leadership.