This piece was originally published in The Guardian on November 23, 2019.

When a Republican, even of the Never Trump variety, cautions the Democratic party against nominating a presidential candidate who is too far left to defeat President Trump in the 2020 election, progressive Democrats rarely respond favorably. They think: why should Democrats take advice from Republicans? Doesn’t such advice amount to “concern trolling”: a disingenuous attempt to undermine the opposing side by pretending to sympathize with it? Aren’t such Republicans trying to get the Democrats to nominate a moderate – in other words, a “Republican lite” – rather than a candidate who will carry out the will of the party’s progressive base?

Such a defensive reaction is understandable – and to some extent justifiable. There are many factors driving Democrats left, not least the outrages of Trump. But one of the most important is the sense by many activists that critical issues were neglected (or at least insufficiently addressed) during the presidencies of moderate Democrats Bill Clinton and Barack Obama.

These issues differ somewhat from activist to activist, but they include growing income inequality, the inability of many workers (especially young people) to get ahead, continuing injustices perpetrated on women and immigrants and people of color, insubstantial efforts against climate change and inadequate healthcare for millions of Americans. In the progressive view, radical change is necessary to take on these challenges, not more incrementalism.

I concede the progressives’ premise but not their conclusion. I believe that far-reaching actions must be taken to address all of these challenges. But I also believe that a Democratic presidential candidate running on too far left a platform would have a considerable likelihood of turning off the moderate middle of American voters, resulting in Trump’s re-election. That’s not a risk Democrats should take.

The (printable) progressive response to that argument is that Trump is vulnerable in 2020, since he has done nothing to expand his base and has never topped a 50% approval rating. Mushy moderates are boring and uninspiring and likely to lose, as Hillary Clinton did in 2016. But progressives who campaign unashamedly on big ideas and a program of vast structural change, like Senator Elizabeth Warren – or even democratic socialism, like Senator Bernie Sanders – will excite the base and hypercharge turnout. Dare to struggle, dare to win, Democrats.

But not so fast … Former president Obama, who remains by far the most popular figure in the Democratic party, agrees that current candidates need to go beyond his accomplishments with new ideas. He recently described his healthcare law, for example, as a “really good starter home”. But he cautioned that even bold visions have to be “rooted in reality” and that candidates have to appeal to “persuadable independents or even moderate Republicans” as well as progressives. “This is still a country that is less revolutionary than it is interested in improvement,” he observed, and “the average American doesn’t think that we have to completely tear down the system and remake it.”

Thomas B Edsall, writing in the New York Times, draws on recent political science research which concludes that extreme, polarizing candidates do worse than moderates because despite their claims of exciting the base they “diminish turnout in their own party while boosting turnout among opposing partisans”. Edsall also cites an October New York Times/Siena College survey of Democratic voters in six battleground states – Arizona, Florida, Michigan, North Carolina, Pennsylvania and Wisconsin – which found that twice as many would prefer a candidate who promises “to find common ground with Republicans” to one who promises “to fight for a bold progressive agenda”. The survey also found a strong preference for a moderate candidate over a liberal one, and a 49% to 45% preference for a candidate who promises “to bring politics in Washington back to normal” as opposed to a candidate who promises “to bring fundamental, systemic change to American society”.

A recent Gallup poll also finds that six in 10 Democrats and Democratic-leaning independents would prefer the nomination of “the candidate with the best chance of beating President Donald Trump, even if that person does not share their views on key issues”. By contrast, only 36% say they would rather have “a candidate aligned with them on almost all the issues they care about, even if that person is not the most electable”.

At the risk of being taken for a concern troll, I would respectfully counsel my Democratic friends to take reality into account when considering their nominee. That means, in part, that they should consider the electorate as it israther than as they might like it to be.

It also means that they should consider the likelihood of their nominee actually being able to pass, and pay for, their legislative priorities. If the Democrats don’t win a majority in the Senate in 2020, then not only is a Warren or Sanders Medicare for All plan a nonstarter, so too is the public-option healthcare plan advanced by candidates like the South Bend mayor, Pete Buttigieg, and former vice-president Joe Biden.

Even if the Democrats gain control of the Senate, they will need the support of conservative Democratic senators like Kyrsten Sinema of Arizona and Joe Manchin of West Virginia. Such senators are likely to balk at the huge tax packages that would be needed to finance the multiple trillion-dollar programs of healthcare reform, student loan forgiveness, free public college, clean energy and other initiatives advanced by several moderate as well as progressive candidates. To expect billionaires alone to pay for all of this is quixotic – particularly since every progressive I know fully expects that billionaires and their lawyers would find some way of weaseling out of whatever taxes might come their way.

A critical attribute of leadership is the avoidance of overpromising. The Republican party has come to grief in recent years because its leaders promised their base that if given congressional majorities as well as the White House they would usher in a rightwing utopia. But they failed because it’s impossible to govern in a divided society without engaging in bipartisan negotiation and compromise.

In fact, political scientists Frances Lee and James Curry found that congressional majority parties hardly ever manage to pass their legislative agenda over minority opposition. They analyzed the legislative priorities of each congressional majority party between 1985 and 2016 and found that the majority party succeeded in passing only 4% of its policy priorities without support from a majority of the minority party and at least one member of its leadership. The party-line votes that passed the Democrats’ Affordable Care Act of 2010 and the Republicans’ Tax Cuts and Jobs Act of 2017 are the exceptions that prove the rule.

So even if the Democrats benefit from another blue wave in 2020, they will have to negotiate with the Republicans to pass significant legislation. That admittedly seems rather unlikely right now, given the Republican stonewalling in the recent impeachment hearings and Trump’s lack of interest in cooperating with Democrats on anything. But the ability to return to some semblance of bipartisanship is another aspect on which the electorate is likely to judge the Democratic presidential nominee.

The critical issue in the next election will not be income inequality, climate change or racial justice, important as all of those are. It will be the preservation of our democratic system that makes reform of those and other issues possible. By the time of the election, Trump most likely will have been impeached by the House but acquitted by the Senate. If given a second term, he will be out for revenge and unrestrained by constitutional checks and the rule of law. Democrats shouldn’t allow that to happen by nominating a candidate in 2020 who’s too far left to win.