The Promise, and Risks, in Turning to Kamala Harris

Vice President Kamala Harris swiftly established herself as the Democratic front-runner to take on Donald J. Trump within hours of President Biden’s exit on Sunday, fundamentally rewiring the presidential contest at warp speed.

Now the race has been transformed into an abbreviated 106-day sprint that more closely resembles the snap elections of Europe than the drawn-out American contests. The tight timeline will magnify any missteps Ms. Harris might make but also minimize the chances for a stumble.

And in a race that Mr. Trump had been on a trajectory to win, Ms. Harris immediately becomes the ultimate X-factor.

Mr. Biden quickly endorsed Ms. Harris, who would be a barrier-breaking nominee as the first woman, the first Black woman and the first person of South Asian descent ever to serve as president. As the Democratic Party rallies behind her — the loudest voices of dissent were simply those not publicly endorsing her — here are six ways her candidacy holds both promise and peril.

During the Republican primaries, Nikki Haley had warned everyone who would listen that the first party to swap out its octogenarian candidate — Mr. Trump will turn 80 while in office if elected to a second term — would win. She was making the argument for herself but the logic applies to Ms. Harris, too.

Unlike the 81-year-old Mr. Biden, Ms. Harris, 59, is not old — and just that fact neutralizes what has been one of the most potent Trump lines of attack.