Brian Snyder / Reuters

If Joe Biden revives his flagging presidential campaign, journalists may record that the revival began this weekend in New Hampshire.

In a series of speeches, Biden finally did what he needed to do weeks ago: He attacked his rivals on health care. He defended the Affordable Care Act, and argued that Democrats should build on it—presumably with some form of public option—rather than embrace a Medicare for All system that bans private insurance. He went after Bernie Sanders by name. “Bernie’s been very honest about it,” Biden declared. “He’s said you’re going to have to raise taxes on the middle class. He says it’s going to end all private insurance.”

This tactical shift was the most politically astute thing Biden has done since he launched his presidential campaign. First, it shows that he’s willing to compete. For months now, Biden has campaigned like it’s the fourth quarter of a game in which he’s far ahead. He’s focused on Trump, not his rivals, in an effort to create the impression that his primary victory is a foregone conclusion. He’s done far fewer events than his chief competitors. And he looked at last month’s debate like someone trying to avoid a blunder, not land a punch.

In so doing, Biden hasn’t only come across as entitled. He’s appeared fragile, if not scared. This weekend he no longer did. For the first time, he looked like a candidate willing to make a direct and substantive case that his centrist instincts are preferable to the party’s recent leftward tilt.

By going on the attack, Biden did something else important: He turned the conversation away from his own record, on which he’s immensely vulnerable. During his nearly half century in politics, Biden has taken so many positions that contemporary Democrats loathe that his rivals could fill every Democratic debate criticizing him. And especially after seeing how ineptly Biden rebutted Kamala Harris’s attack on busing, it’s likely that the other top competitors are sharpening their swords. When the next debates begin later this month, it’s easy to imagine Sanders going after Biden for his vote for the Iraq War or Elizabeth Warren accusing him of making it harder for families to declare bankruptcy. These duels would be hard for Biden even if he were an immensely skilled debater, which he no longer is.

Biden needs to approach the primary campaign like Barack Obama approached the 2012 general election, when his approval ratings hovered below 50 percent: He needs to delegitimize the opposition. And health care is Biden’s best chance. It’s his best chance because his position—Obamacare plus a public option—is more popular even among Democrats than the Sanders/Warren position of Medicare For All without private insurance. When the Kaiser Family Foundation asked Democratic voters in January what they wanted congressional Democrats to prioritize, protecting and improving the Affordable Care Act beat passing Medicare for All by 13 points.

Drawing a clear contrast with Sanders and Warren also reminds commentators, and voters, that Harris hasn’t been clear on health care at all. Twice already—first at a CNN town hall in January and second at last month’s debate—Harris has indicated that she’d abolish private insurance only to reverse herself. She also failed to answer a Washington Post survey on the issue. So at the same time as he paints Sanders and Warren into an ideological corner, Biden has the chance to paint Harris as someone who can’t make up her mind.

Finally, focusing the campaign on Obamacare versus Medicare for All highlights Biden’s greatest political strength: the perception that he’s the Democrat best able to beat Trump. If scrapping private insurance is a loser among Democrats, it’s an even greater loser among Americans as a whole. As the January 2019 Kaiser poll notes, support for Medicare for All drops to only 37 percent when Americans are told it would eliminate private insurance. That’s an awful number for a party that has consistently relied on its advantage on health care to win elections. By emphasizing how unpopular abolishing private insurance is, Biden can give substance to his electability argument. It’s no surprise that this weekend in New Hampshire, while attacking his opponents on health care, Biden also noted that he was the only presidential candidate invited to campaign for congressional candidates in conservative states like Montana and North Dakota.

Biden can’t credibly pretend to be as progressive as Sanders, Warren, or even Harris. But he doesn’t need to. He needs to win big among Democrats who call themselves “moderate” or “conservative,” who together still constitute close to 50 percent of the party’s voters. And the good news for him is that Pete Buttigieg and Amy Klobuchar, the other major candidates aggressively seeking the center lane, are polling in the single digits.

Defending Obamacare was the Democrats’ strongest issue in the 2018 midterms, and it’s Biden’s strongest issue today. Sanders, Warren, and Harris gave him an opening with their answers on eliminating private insurance at last month’s debate. In New Hampshire, he finally took it.

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