In recent columns I have celebrated the energy and ideas brought into the Democratic party by newly-elected young leftists, defended them from criticism, condemned the red-baiting of the left, and explained how and why “socialism” has played an important role in the history of American democracy, and ought not to be feared.

I have been making these arguments for the past three years, going back to Bernie Sanders’s entry into the 2016 Presidential race (see here and here and also, a bit more skeptically, here).

I think it is a huge error to exaggerate the differences separating “democratic socialists” like Sanders and “Progressive liberals” like Elizabeth Warren. And while I think vigorous debate about principles and policies is essential, I think it is also a huge error for these debates to become acrimonious or to become centered on abstract labels rather than concrete principles and policies. For it will be necessary, at some point in the summer of 2020, for all of the contestants to come together behind the winner of the primary, in order to defeat Trump and his Republican enablers. This will not be the end of debate, for the 2020 election will not be the last election — hopefully! — and democracy is an ongoing and unfinished project. But it will be the time to put some of the most heated debates on temporary hold, and to work together to support a Democratic victory.

As a left liberal who retains some sense of connection to his neo-Marxist roots — and who rejoined Democratic Socialists of America, after a 20-year hiatus, on the day after Trump’s election — I personally lean in the general direction of Sanders and Warren, whose platforms are the most “left” of the many Democratic contenders.

There is much legitimate excitement about the revival of the left, and I strongly believe in supporting this energy and excitement; as I said only last week in praise, “New Blood Brings New Energy to the Democratic Party.” But I’ve also seen and experienced too much in my six decades to fully share in this enthusiasm. And I am painfully cognizant of the fact that while there is much discontent, and while the left has made headway in some important quarters, American society in 2019 is not fertile ground for democratic socialism. More importantly, the American state is being governed — or rather, mal-governed — by an aspirational fascist who, while he has no majority, does have a very strongly mobilized base, and has the power to create emergencies, and is doing his best to wage a campaign of vicious red-baiting.

In short, there are no guarantees that Trump will be defeated in 2020. He might well win, through some combination of an orchestrated crisis, a highly mobilized base, i.e., his mob, and acrimonious divisions among his opponents.

And while the left has gotten many headlines — many due to the charisma of Alexandra Ocasio-Cortez, who I have repeatedly celebrated — and has advanced important proposals, like Medicare for All and the Green New Deal, this does not mean that the left is a hegemonic force. While fine high-profile left candidates like AOC and Rashida Tlaib won in November, most of the Blue Wave involved centrist victories. That is a fact.

While the Democratic party now includes socialists and must respect these socialists, it is not yet, and is not likely to ever be, a socialist party. This means that it has many currents, and leaders, who are not socialist and who do not believe in socialism. These currents, and leaders, need to be recognized for what they are. And leftists and socialists who are now working inside the Democratic party and supporting leftist Democratic leaders like Bernie Sanders and Alexandria Ocasio-Cortez need to understand that they need to argue with and sometimes challenge these other leaders, but also must work with them, and in all probability work in a context in which it is these leaders, and not the leftists, who will have the upper hand. This is simply how the balance of forces leans in the Democratic party — and until the U.S. adopts a different form of representation, and becomes a multi-party system, the Democratic party is where the action is on the left when it comes to national politics.

This is true even if Bernie Sanders is chosen as the Democratic nominee — something that is by no means assured, and about which I personally remain agnostic.

Today’s Democratic primary field is very wide. It includes Sanders and Warren, and also Kamala Harris, and Corey Booker, and Kirsten Gillibrand, and many others. There is significant and healthy disagreement on the broad democratic left about these choices, each of whom represents — in all meanings of “representation” — things worth supporting. The competition will be and should be hard, and the debate honest and sharp. Much is at stake, and it is important both to win an election and to project a vision for the future.

At the same time, any Democrat will face tough going in 2020 in a race with Trump. And because defeating Trump is so important, it is also important that the debate not be acrimonious, and that it promote a productive agonism based on mutual respect and understanding.

And this brings me to Kamala Harris.

Harris is not my favorite candidate. At the same time, she is in many ways a compelling candidate. Some have likened her to Barack Obama. Some have celebrated this, and others have regarded this as a sign of her less-than-vital “centrism.” Legitimate criticisms have been made of her, especially regarding her record as a prosecutor and California Attorney General, and her responsiveness to the concerns of groups like Black Lives Matter. Harris’s positions on such things are fair game. At the same time, it is important for those farther to the left to understand that Harris is simply not that far to the left, and this does not make her stupid or evil or hypocritical, it simply makes her different than the preferred candidates of the left.

Why is it important to say this now? Because of a dust-up last week that has received much attention, and that has already contributed to a further poisoning of Harris’s candidacy among some on the left. A Common Dreams headline neatly explains: “In New Hampshire, Kamala Harris Makes Clear That She is Not With the Democratic Socialists.” The Daily Beast headline said it more directly: “Sen. Kamala Harris: ‘I am Not a Socialist.’” As these headlines flashed across my Facebook feed last week, they were followed by an outpouring of outrage from friends on the left. “I can’t believe she is doing this.” “She’s red-baiting already?” “So, the way she is selling herself is by dissing the left?” “There is no way I can ever support someone who says this.”

I understand this reaction. A version of this was my initial reaction as well. I didn’t like the tone of the headlines. I was primed to be concerned about the red-baiting that Trump has already commenced. And I wondered. But I was also a bit skeptical. And so before doing anything else, I went to the Tweeted video of Harris’s much-reviled comment, and watched. Here is a full rendering of the situation:

Question from reporter: “Senator Harris, one of the most popular Democrats in America right now is the guy who won here in 2016. Bernie Sanders describes himself as a democratic socialist. To compete in New Hampshire in the Democratic primary, do you have to move more toward the democratic socialist part of the party?”

Answer from Harris (with a smile): “Well, the people of New Hampshire will tell me what’s required to compete in New Hampshire, but I will tell you that I am not a democratic socialist, I believe that what voters do want is they want to know that whoever is going to lead understands that in America today not everyone has an equal opportunity and access to a path to success, and that that has been building up over decades and we’ve got to correct course. When we have an America where almost half of Americans cannot afford a $400 emergency, we know that we’ve got to do some course correction. When we have an America where 99% of the counties in America, if you are a minimum wage worker who are working full time you can’t afford market rate for a one-bedroom apartment, we need to course correct. And those are my commitments, in terms of being able to be in a position where I see it, also I intend to do something about it.”

Harris then continued: “I’m not a democratic socialist. I believe that capitalism has great strengths when it works for all people equally well. I believe we also do need to recognize that over the last many decades the rules have been written in a way that has excluded working families and middle-class families and we’ve got to correct course. That’s why I’m proposing, for example, that we change the tax code . . .”. She then talked about tax credits for working poor families and renters.

Now, say what you will about her ideas here, there is nothing “red-baiting” about them. Asked by a reporter about whether she is “a socialist” — the mass media are eager to turn this into a melodrama about Bernie and AOC and the “socialist” label — she responded, in measured fashion, by explaining where she stands: she is not a socialist, but she believes in substantial reforms to mitigate the inequalities of capitalism. Her answer was, indeed, rather progressive. But, more important, it was honest. For she is not a socialist.

As someone who first joined DSOC (Democratic Socialist Organizing Committee), the precursor to DSA, in 1976, while a student at Queens College, I can only be amazed that this question is now being posed to a major Presidential candidate — a Black woman no less — and even more amazed that there are some on the left who can regard the answer as a litmus test, in which the statement “I am not a socialist” becomes a badge of dishonor.

Harris is not a socialist. Neither is Booker or Gillibrand or Warren, or Pelosi or Schumer or Adam Schiff or Elijah Cummings or Maxine Waters or Stacey Abrams or Andrew Gillum. Indeed Waters, long an icon on the left, declared forthrightly last December, in an interview with John Harwood, that “The Democratic Party is not a socialist party. . . I just don’t think our party should be identified because we have a few people who seem to be to the left of the left.” She said this in the context of a rather powerful and perhaps even characteristically belligerent discussion of her strong opposition to Trumpism. Again, those who are socialists will take a different view. But she simply spoke the truth. She is not a socialist. The Democratic party includes some socialists but is not socialist. And indeed, most Americans are not socialist. And if you interpret any opinion poll, by Pew or anyone else, to suggest otherwise, then you are being very naïve about the difference between filling out a questionnaire and knowingly committing oneself to a cause that involves sustained, radical change.

It needs to be possible for Democratic politicians, even and especially Democratic politicians on the broad left, to be able to say this without being considered to be “red-baiters” or reactionaries.

As I have argued many times, and as I will continue to argue, the activism and voter mobilization and policy positions of self-identified socialists like Sanders and AOC are a breath of fresh air in the Democratic party. The party needs to take these leaders, and their constituencies and voters and ideas, very seriously. They ought to be given a fair chance to win out, in the primaries, in the platform debates, and in politics more generally. But this does not mean that those Democrats who are more centrist or moderate or even left-but-not-left-enough-for-some are doing something underhanded or wrong by standing for what they stand for.

Those left activists who have done so much to support leaders like Sanders and AOC, and to support local organizational efforts to promote left issues and policies, have every reason to expect the Democratic party to take them seriously and to refuse and denounce all right-wing efforts to red-bait left Democratic candidates. But they have no reason to expect the many Democratic leaders and voters who are not on the left to agree with them. The debate within the Democratic party has shifted to the left, and this is good. But it is still a debate within the Democratic party, which is not a seminar or a town meeting but an organization with real institutional investments and mobilizations of bias. And as the election approaches, it is a debate that will center on two linked questions: which candidate, and which platform, can mobilize core Democratic constituencies, and which candidate and platform can win the 2020 election.

Let this debate, and this contest, unfold, in a spirit of respectful agonism and agonistic respect.

Jeffrey C. Isaac is James H. Rudy Professor of Political Science at Indiana University, Bloomington. He is a Senior Editor at Public Seminar, and his book #AgainstTrump: Notes from Year One, was recently published by Public Seminar/OR Books.