The first Democratic debate was always destined to be about Elizabeth Warren, and she seized the initiative with the first question.

The U.S. senator from Massachusetts smoothly took a question about the economy by saying, “It’s going great for a thinner and thinner slice at the top,” singling out drug companies and oil companies at the expense of, say, African-Americans.

And the sound bite: “That is corruption, pure and simple.”

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The next few candidates offered variations on the same theme. Amy Klobuchar, proposing free community college, was the first to take a shot at President Trump. Beto O’Rourke said, “This economy has got to work for everyone” before breaking into Spanish — and ducking a question about whether he supports a 70 percent tax rate. Cory Booker hit the same note, talking about his less-than-affluent minority neighborhood. Tulsi Gabbard said she would “put your interests ahead of the rich and powerful.”

The MSNBC moderators didn’t distribute the time evenly among the 10 contenders in Miami. Warren got several questions in the first half-hour and demonstrated a finely honed sense of slamming corporate America.

Too many big companies, she said, care only about profits and are quick to move jobs to Mexico, Canada or Asia. At another point, Warren declared she was “calling out the monopolists.”

The senator also gave a passionate answer on why she backs Medicare for All — but totally ducked the question about why it was all right to eliminate private insurance for 150 million Americans. Even when she had a second bite of the apple — complaining that insurance companies “sucked $23 billion in profits out of the system” last year — there was no effort to pin her down on forcing people to give up their private coverage.

That was a central weakness of the MSNBC approach. Lester Holt and Savannah Guthrie asked bread-and-butter policy questions, but under severe time constraints, made only a couple of token efforts to press the candidates who ignored the thrust of their questions. O’Rourke wouldn’t answer on whether he supports a 70 percent tax rate, even when his fudge was pointed out.

The moderators never really challenged the candidates with another viewpoint in the first hour. Holt and Guthrie didn’t ask about limitations on late-term abortion. They didn’t say, "Hey, doesn’t a country need some border enforcement?' They didn't say, "Hey, are you really going to blow up private health insurance for an all-government program?" The entire debate was safely conducted within the confines of liberal orthodoxy.

(In the second hour Chuck Todd was more aggressive and wide-ranging, calling out Warren when she sidestepped his specific question on guns; pressing Klobuchar on gun confiscation, and raising the cost of fighting climate change. Rachel Maddow, a liberal opinion host, read scripted questions that were straightforward but also alone the lines of, "Are you doing enough to mobilize black and Latino voters?")

The Democrats vied with each other on their passion to protect abortion rights, but couldn’t match Warren, who said they can’t rely on the courts and Congress needs to enshrine Roe v. Wade into federal law.

On this and other issues, the candidates were literally playing to their base. There was virtually no effort to reach out to Republicans or independents who might not subscribe to the left-wing line. Some of them sounded like open-borders advocates or pretty close to it.

There were only flashes of debate among the candidates, such as a dustup over illegal immigration between O’Rourke and Julian Castro, which became incomprehensible as they cited sections of various laws.

I was mildly surprised there wasn’t more Trump-bashing, beyond the occasional whacks. But the group had decided collectively it was more important to push their policies and introduce themselves to the television audience.

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If there was a dark horse as a strong debater in Miami, it was Bill de Blasio, but unfortunately for him, even a majority of New Yorkers didn’t want him to run.

In fact, Gabbard’s sister tweeted on her account: “It's clear who MSNBC wants to be president: Elizabeth Warren. They're giving her more time than all the other candidates combined.” (This was literally untrue.)

In part because of that boost, Warren was the winner on several counts. She was crisp and confident, had a consistent theme — corporations are ruining America — and no one took a shot at her. She projected heartfelt anguish on the question about school shootings.

Warren lucked out in the lottery, with the other top-tier candidates — Biden, Sanders, Buttigieg, Harris — slated for Thursday night. And she made the most of that opportunity.