Joe Biden won the first presidential debate by default. Against the meltdown of a desperate incumbent who is staking his claim to a second term on racist dog-whistling to hate groups and open disdain for democracy, the challenger barely had to open his mouth in order to appear more presidential than the charlatan who currently occupies the Oval Office.

Yet if Biden’s goal is to actually occupy the office, and to do so with a mandate sufficient to govern, he should stop stepping into the traps that Trump lays—in the debates to come and in the last month of the 2020 campaign. In particular, the former vice president must stop apologizing for being the candidate of a party that includes democratic socialists with popular ideas. Like Franklin Delano Roosevelt and Harry Truman in the 1930s and ’40s, Biden has to recognize that the way to build a winning coalition is to worry less about attacks from rivals who seek to divide Democrats and more about delivering messages of his own that unite the party and extend its appeal.

Biden’s defensiveness got the better of him during the debate, when the discussion turned to health care policy. Trump charged that the Democrat is “going to extinguish 180 million people with their private health care.” Biden replied, “That’s simply not true.” Then Trump said, “Well, you’re certainly going to socialist. You’re going to socialist medicine…”

Trump was claiming that his challenger would move the country toward a single-payer Medicare for All health care program, which recent polling finds it is supported by 69 percent of all Americans and 88 percent of Democrats. When Biden pointed out that he has campaigned as a candidate who “wanted to allow people to have private insurance still,” Trump was having none of it. He baited the Democrat, and Biden got even more defensive:

Trump: That’s not what you’ve said and it’s not what your party is saying.

Biden: That is simply a lie.

Trump: Your party doesn’t say it. Your party wants to go socialist medicine and socialist health care…

Biden: The party is me. Right now, I am the Democratic Party.

Trump: …and they’re going to dominate you, Joe. You know that.

Biden: I am the Democratic Party right now.

Trump kept looking for ways to divide the Democratic coalition, and Biden kept distancing himself from some of the most vibrant ideas and leaders within that coalition. The president said, “Joe, you agreed with Bernie Sanders, who’s far left, on the manifesto, we call it. And that gives you socialized medicine.” Biden shot back, “The fact of the matter is I beat Bernie Sanders.” Trump said, “Not by much.” Biden said, “I beat him by a whole hell of a lot.” Trump repeated, “Not by much.” An agitated Biden said, “I’m here standing facing you, old buddy.” Making a crude reference to the candidacy of Massachusetts Senator Elizabeth Warren, Trump said, “If Pocahontas would have left two days early, you would have lost every primary. On Super Tuesday, you got very lucky…” Biden replied, “I got very lucky. I’m going to get very lucky tonight as well.” And then they started arguing about something else.

Biden got equally defensive later in the debate, when Trump started ranting about the Green New Deal—alleging that it would cost “$100 trillion,” and that its proponents “want to take out the cows.” Instead of laughing off a president who spins pure fantasy, Biden distanced himself from the response to climate change that has been championed by Representative Alexandria Ocasio-Cortez (D-N.Y.) and Senator Ed Markey (D-Mass.) as well as the Sunrise Movement. “I’m talking about the Biden plan,” responded the former vice president, who moments later said, “I don’t support the Green New Deal.”

Trump seized on that one. “Oh, well, that’s a big statement,” he said. “You just lost the radical left.” He tried a similar line during the socialism section of the debate, because it is the president’s desperate desire to get Biden fighting with the left. Trump’s goal is transparent: He wants to get Biden to say things that will discourage potential voters who are attracted to socialist and progressive proposals. Biden shouldn’t fall into the trap.

The fact is that AOC and Sanders and a number of other prominent democratic socialists are campaigning for the Democratic ticket, with the message that Trump must be beaten. While they recognize differences on issues such as Medicare for All and the Green New Deal, Sanders and AOC suggest that they can work with a President Biden—just as the most successful Democrats of the past, especially FDR, worked with the left-wing of the party, and the broader left.

Roosevelt met with, worked with, and borrowed phrases (“economic royalists”) and ideas from socialists—to such an extent that his Socialist Party challenger in the elections of 1932, 1936, 1940, and 1944, Norman Thomas, would eventually say, “Roosevelt’s New Deal was not the best alternative, but it certainly was a better alternative than had been offered to the problems of our times, and it was offered with an elan, a spirit that made things go and which tended to lift up people’s hearts. In retrospect, I wouldn’t change many of the criticisms I then made. Yet the net result was certainly the salvation of America, and it produced peacefully, after some fashion not calculated by Roosevelt, the Welfare State and almost a revolution.”

Part of Roosevelt’s genius was that he learned to talk about socialist ideas and socialist activists in congenial ways that welcomed ideas without being defensive. In a letter to Dan Hoan, the longtime Socialist Party mayor of Milwaukee, FDR wrote that “it makes no difference whether you call yourself a Republican, Socialist, Democrat or Hottentot. The point is that you have contributed greatly both to the theory and practice of local government.”

Roosevelt didn’t run around bragging about how he beat the socialists or the progressives or the backers of bold reforms. Neither did Truman, who developed the perfect response to rivals like Trump. “Socialism is a scare word they have hurled at every advance the people have made in the last 20 years,” explained Truman. “Socialism is what they called public power. Socialism is what they called social security. Socialism is what they called farm price supports. Socialism is what they called bank deposit insurance. Socialism is what they called the growth of free and independent labor organizations. Socialism is their name for almost anything that helps all the people.”