O NE OF THE reasons—maybe the biggest reason—why Joe Biden is ruling the Democratic primary field is an apparent paucity of convincing alternatives. Pete Buttigieg is dripping with talent, but struggling to reach beyond the liberal MSNBC crowd. Elizabeth Warren is an intellectual heavyweight, yet making little headway in a contest that seems increasingly defined by a single question: can you beat Donald Trump? In that tremulous environment, the reassuringly experienced former vice-president is putting everyone else in the shade. He leads his nearest rival, Bernie Sanders, by 20 points. Yet there is one candidate of whom more brilliance might have been anticipated. Kamala Harris, the first-term senator from California, is stuck in single digits despite a strong launch and early fundraising. She is the contest’s most conspicuous under-performer. Lexington went to watch her campaigning in Las Vegas last week to try to work out why.

Her events there, first a meeting with Asian-American leaders in a Vietnamese restaurant, then a gathering of Hispanics in a Mexican one, pointed to a reason why much is expected of her. A high-achieving daughter of an Indian mother and Jamaican father, whose state has more Hispanics than any other, Ms Harris encapsulates the changing Democratic Party. “First and foremost, seeing you as a woman who identifies as Indo-Caribbean makes me happy!” said a woman nursing a baby at the first rally. And Ms Harris’s focus on Nevada, an early-voting state next to California, reflects a primary schedule that is another potential strength. If she can emerge from the opening contests in Iowa and New Hampshire looking competitive, the next tranche, including large and diverse states such as California, could put her over the top.

Her room-grabbing presence, also on show in Vegas, is a bigger advantage. A diminutive former state attorney-general, she combines the authority of a prosecutor with the all-aglow enthusiasm, for whoever is put in front of her, of a skilful retail politician. It helps that she looks and sounds good, a quality Barack Obama once remarked on, in a rare faux pas, when introducing her as “by far the best-looking attorney-general in the country”. To be sure, a black woman vying to take on Donald Trump also faces hurdles. After the president’s misogynistic treatment of Hillary Clinton, some Democrats consider an elderly white man, per se, a safer bet for their nominee. The fact that Mr Trump has already labelled Ms Harris “nasty”—an adjective he applied to Mrs Clinton—suggests they might be right. Yet those who believe Ms Harris is being unfairly judged on her race and sex should hold fire.

First, because on the slippery question of “electability” her profile and attributes have already given her a sizeable, not particularly fair, advantage over similarly qualified candidates. Why else did she enter the race with such a lead over Cory Booker and Amy Klobuchar? Accomplished though she is, Ms Harris’s Senate career has been brief and unmemorable, aside from a few tough exchanges with administration officials in the Judiciary Committee. Moreover, as her performance in Las Vegas also attested, she is doing an indifferent job of capitalising on her opportunity.

She has accrued a reputation for excessive caution. Asked about reparations for African-Americans, votes for prisoners or any other hot-button issue, she almost invariably expresses a keenness to contemplate the matter further. She has attributed this tendency to a lawyerly fastidiousness about the facts; yet she is sometimes rash. Under the tutelage of her sister Maya (Mrs Clinton’s former policy guru), she seems determined not to get outflanked by the left on any issue, whether she fully grasps it or not. Hence her support for Medicare for all, free college, fining companies that fail to narrow their gender pay-gap, and her embarrassing, later retracted, suggestion that she would scrap private health-care insurance. And still no one believes she is a proper leftie.

She spent most of her career as a tough-on-crime prosecutor (she famously criminalised the parents of truants). And when not vowing to support the latest left-wing fad, she sounds strikingly unideological. Her stump speech, which is based on an idea that America needs more “truth and justice”, is a painfully contrived effort to marry her strengths to a critique of Mr Trump. It neither informs nor inspires. It has nothing of the revolutionary fire that consumes Mr Sanders. The overall impression is of a talented, centre-left opportunist who has not quite found her place in her party, let alone the distinctive voice voters crave. Her attempt to fight the primaries on the left, where she has shallow roots, has only made this more obvious. It is probably also mistaken, given Mr Biden’s success and the moderate instincts of the non-white voters she is banking on. “Asians just want someone who won’t throw us out of the country,” said a Chinese-American businessman at Ms Harris’s first event. Ideally, he said, that person would be a moderate—as he thought Ms Harris probably was.

Karma Kam-eleon

At least the ambiguity surrounding Ms Harris gives her room for manoeuvre. In imitation of Mr Biden, she is ramping up her attacks on the president, including by arguing for his impeachment. This is another bid to underline her ability to “prosecute the case against Trump”, as she says. But it is unclear who would be likelier to vote for her as a result. Most Democrats want the candidate they consider likeliest to beat Mr Trump, which requires general-election votes, not pugilism. Yet the shift could at least give her space, if she is wise, to reappraise her default leftishness.

She probably cannot beat Mr Biden that way. By the same token, however, his surge looks even more daunting for inflexible leftists such as Mr Sanders. That could make it a net gain for Ms Harris. Ill-prepared and too calculating though she seems, she still looks well-placed to take over from Mr Biden if he stumbles, as he easily may. Ms Harris seems to be a lucky politician. Whether her luck would hold out against Mr Trump is another matter.