Vice President Mike Pence just got some very bad news. He’s going to lose the vice presidential debate this fall, and that loss is going to do serious damage to the already diminished 2020 election prospects of the Republican Party.

California Senator Kamala Harris will shred Donald Trump’s hapless running mate when the two confront each other during the vice presidential debate on October 7 at the University of Utah.

That’s not the only reason presumptive Democratic nominee Joe Biden chose Harris as the Democratic vice presidential nominee. Harris brings to the ticket youth, as a candidate 22-years younger than the party’s presidential pick, and diversity, as the daughter of Indian and Jamaican immigrants who will be the first woman of color to run on a major party ticket. She has the sort of experience in local, state, and national politics that Biden appreciates. She’s more liberal than Biden on a number of issues, but she’s certainly not a progressive along the lines of Vermont Senator Bernie Sanders or New York Representative Alexandria Ocasio-Cortez. That frustrates the left, which pushed for Biden to consider VP prospects such as Massachusetts Senator Elizabeth Warren and Congressional Progressive Caucus chair Karen Bass. But by now it is clear that the former vice president and his ideologically cautious inner circle are planning to run a campaign that puts a bigger emphasis on beating Trump and Pence than it does on scoping out the sort of bold, structural change that Sanders and Warren proposed with their 2020 presidential bids.

Biden recognizes that, despite encouraging poll numbers, he’s in a serious fight. And he appreciates, from his own experience, that Harris is a sharp and aggressive campaigner who will pull no punches when it comes to calling out her opponents and commanding a debate stage.

Biden is a political structuralist. He knows where the pivot points are in campaigns and he knows that the pundits are always wrong when they neglect the role that vice presidential candidates play in defining the course of presidential campaigns. Biden is, after all, one of the few Americans who can unquestionably be said to have won two vice presidential debates—against Alaska Governor Sarah Palin in 2008 and against soon-to-be Speaker of the House Paul Ryan in 2012—at critical points in races for the White House.

The 2008 win was important because it closed off some of the last hopes for the flailing Republican ticket of Palin and Arizona Senator John McCain in a race with a dynamic young Democratic presidential nominee, Barack Obama, and a vice presidential nominee who was clearly more competent than his rival.

The 2012 win was even more important, because it came after an initial presidential debate in which Republican nominee Mitt Romney had dramatically exceeded expectations, a development that led pundits to speculate that President Obama and Vice President Biden could indeed be beaten. Republicans just “knew” that Ryan, who they still imagined was their cool, smooth “ideas guy,” would run circles around the gaffe-prone Democrat who Time magazine suggested had a brain that was “wired for more than the usual amount of goofiness.” It didn’t work out that way. Biden came out swinging so hard when the two candidates met in Danville, Ky., that Ryan did not know what hit him. It was all over when Ryan pitched his Wall Street–approved scheme for “reforming” Medicare and Biden looked at the camera and said, “Folks, use your common sense: who do you trust on this?”

Biden, who will have his hands full debating the wily and cruel Trump this fall, wants his running-mate to finish off Pence just as effectively as he finished off Palin and Ryan. The presidential debates will still matter most, of course, but the Democrats need to build momentum at every turn, and a pummeling of Pence by Harris will do that. And Biden knows Harris will crush Pence. After all, she showed Biden no mercy when they clashed in the most dramatic moment of the 2020 Democratic presidential debates.

Much has been made of Harris’s confrontation with Biden—during the first round of Democratic debates in June 2019—over statements he had made praising segregationist senators, as well as his opposition to court-ordered school busing. The exchange, in which Harris recalled her own experience as “a little girl in California who was part of the second class to integrate her public schools,” was aptly described by Vox as “the standout moment of the entire first debate.”

With masterful skill, Harris combined a powerful policy critique with poignant personal history as a Black American who came of age during the busing fights of the 1970s. Her command of the debate stage was so striking that few honest observers debated the conclusion of The New Yorker:Harris won the night.”

Harris got a boost, but she never overtook Biden. As the race picked up steam, she faded. Like Biden in 2008, she was a presidential candidate with obvious skills, yet her campaign never figured out how to chart a path to the nomination.

But here’s the twist. Even as she fell in the polls, Harris continued to turn in stellar debate performances. She wasn’t just solid. She was compelling, effective, and memorable. She held her own against other candidates—when they attacked her and when she was going after them—and just as importantly, she came at issues with bold and quick-witted language. It wasn’t necessary to agree with Harris—and I often did not—to recognize that had she been nominated, she would have pummeled Donald Trump in the fall 2020 debates.

A Politico review of a November debate summed things up well:

Harris put in a solid showing, commanding plenty of speaking time while continuing to hammer the central message that she’s best equipped to defeat Trump. She made an impassioned appeal for her ability to “rebuild the Obama coalition” and court Black voters—a critical part of Harris’s potential path to the presidency—rebuking Democrats who “show up in a church” during election season but neglect “the backbone of the Democratic party.”

And she nailed it in the foreign policy debate, where she had the crowd laughing and cheering when she declared that the president “got punked” by North Korean leader Kim Jong-un.

The Harris campaign had its problems, as has been well documented. The New York Times suggested that it had “unraveled” even before she quit. But if debates mattered as much in the primary season as they will in the fall, the strength of her presentations—not just in the first round but also in those that followed—would have gotten much further.

Joe Biden saw that. Even as some of his aides continued to resent Harris for showing up their boss, Biden had the political insight and flexibility to recognize what the Californian brought to the debates in which they faced each other—and the fierce urgency Kamala Harris will bring to the debate with Mike Pence and the remainder of the 2020 campaign.