What most politicians and most pundits fail to recognize about impeachment is that it is not just a process. It is a test.

Do they get it, that members of Congress determine whether our shared Constitution is real? That the Constitution sets clear standards that must be applied? That those standards are intended to check and balance abuses of power? And that when those checks and balances are embraced by Congress, it is not a “constitutional crisis” but, rather, the cure for a constitutional crisis?

What is striking about Elizabeth Warren, although perhaps not surprising, is the extent to which she gets it. She understands that when members of the legislative branch are alerted to wrongdoing by the head of the executive branch, they are not supposed to muddle their messages or make political calculations. They are supposed to speak of impeachment.

It appears that House Speaker Nancy Pelosi and the Democratic leadership of the chamber may finally begin to offer a coherent response that includes the “i” word.

But Warren has been doing this for months. Indeed, the Massachusetts senator began speaking up at a point when top Democrats in the Congress and more than a few presidential contenders were hedging their bets. In April, when she was far from a front-runner for the Democratic presidential nomination, Warren distinguished herself with a full and knowing embrace of the Constitution. On a long plane flight, the former law professor read the redacted report from special counsel Robert Mueller, came to a conclusion grounded in her understanding of the system of checks and balances, and acted according to the dictates of the founding document.

“The Mueller report lays out facts showing that a hostile foreign government attacked our 2016 election to help Donald Trump and Donald Trump welcomed that help. Once elected, Donald Trump obstructed the investigation into that attack,” she announced. “Mueller put the next step in the hands of Congress: ‘Congress has authority to prohibit a President’s corrupt use of his authority in order to protect the integrity of the administration of justice.’ The correct process for exercising that authority is impeachment.”

This was not a jarring or radical statement for those who have actually read the Constitution. Rather, it was a savvy interpretation of how the document applied to the Mueller report by someone who is competing for the right to swear an oath, on January 20, 2021, to “preserve, protect and defend the Constitution of the United States.”

Warren spoke in the direct, unequivocal language that Americans have a right to expect from the president who will have to clean up the mess made by Donald Trump. While other contenders addressed the Mueller report—and some like Julian Castro, Beto O’Rourke, and Pete Buttigieg were quick to mention the prospect of impeachment—it was Warren who went to the heart of the matter: “I took an oath to the Constitution of the United States,” she said, “and the Constitution makes clear that the accountability of the president is—lies through Congress, and that’s the impeachment process.”

More candidates have called for an impeachment inquiry since then. But Warren’s voice has been the steadiest, and the most determined. She has spelled out the case for impeachment in television interviews, she has integrated it into her presidential bid, and she has taken it to the Senate floor—telling the chamber in May,

This is not a fight I wanted to take on, but this is the fight in front of us now. This is not about politics. This is about the Constitution of the United States of America. We took an oath—not to try to protect Donald Trump. We took an oath to protect and serve the Constitution of the United States of America. And the way we do that is we begin impeachment proceedings now against this President.

Last week, when a whistle-blower opened up a new discussion about President Trump’s pressuring of the Ukrainian president to ramp up investigations into the son of former vice president Joe Biden—a prominent political rival—the need to impeach became clearer. So, too, did the cost of failing to impeach, as Warren immediately explained.

“After the Mueller report, Congress had a duty to begin impeachment,” she argued on Friday. “By failing to act, Congress is complicit in Trump’s latest attempt to solicit foreign interference to aid him in US elections. Do your constitutional duty and impeach the president.”

The charge of complicity was blunt; some might suggest it was risky. But it was necessary to move the discussion in the direction it needed to go—as Representative Alexandria Ocasio-Cortez noted: “At this point, the bigger national scandal isn’t the president’s lawbreaking behavior. It is the Democratic Party’s refusal to impeach him.”

Like the Harvard Law professor that she was before she stepped on to the national stage, Warren made the case again last Friday. “A president is sitting in the Oval Office, right now, who continues to commit crimes. He continues because he knows his Justice Department won’t act and believes Congress won’t either. Today’s news confirmed he thinks he’s above the law. If we do nothing, he’ll be right.”

Over the weekend, at forums and rallies, Warren kept making impeachment an election issue, as is entirely appropriate. Those who seek to lead should lead. And Warren was doing so on Tuesday morning when she dispatched a two-sentence tweet that said everything that needed to be said: “The House must impeach. It must start today.”