No one, as Donald Trump might say, has ever seen anything like it.

A presidential contest lasting just over 100 days — less time than it takes to complete a Major League Baseball season, or to gain fluency in a second language.

The brevity is, of course, a function of Joe Biden’s catatonic debate performance, ensuing Democratic panic and the president’s overnight replacement in the shank of summer by his vice presidential understudy, Kamala Harris.

Since then, every day has seemed like a week in normal campaign time. Every week has been like a whole month.

And yet while the snap election is unprecedented, there is a rough analog.

Just about 20 years ago, Republican Arnold Schwarzenegger unexpectedly sprang forth on late-night television and launched his candidacy for California governor as part of a madcap vote on whether to oust Democrat Gray Davis. Schwarzenegger’s campaign lasted barely two months and ended with the Hollywood super-duper-star elbowing aside the beleaguered incumbent.

Different times, different circumstances. But there are noteworthy parallels between the recall election and the current demi-race for president. Not least are the advantages enjoyed by both Schwarzenegger and Harris as a result of the drastically truncated campaigns they dived into.

One is the novelty of the two candidates.

“She continues to be fresh and different,” said Don Sipple, a veteran political ad man and top strategist for Schwarzenegger, who — like Harris — ran promising bone-weary voters a change from the same old same old. “That’s not something that’s going to hold for a year and a half.”

The collapsed time frame has also allowed Harris to slingshot, as Schwarzenegger did, from one big campaign event to the next, with scarcely a lag in between.

Presidential contests, Sipple said, are typically decided by a series of headline-and-meme-generating moments: “Conventions. Acceptance speeches. Debate performances. Her anointment was followed by a very successful convention and a very successful convention speech. And just when that was starting to wear off, she went one-on-one with Trump and acquitted herself nicely in their debate.”

All of that has delivered a strong jolt of momentum to Harris, with less than six weeks remaining until election day. Or, it should be said, with less than six weeks left until the balloting ceases on Nov. 5.

Voting has already started in three states, Minnesota, South Dakota and Virginia. By this time next week, balloting will be underway in four more, including the battlegrounds of Michigan and Pennsylvania. By mid-October, more than a dozen states — including California — will be voting.

There’s still plenty of campaigning to go. But with every ballot cast, each day’s developments — an endorsement, a policy pronouncement, a stumble, a gaffe — become that much less significant.

Apart from an abbreviated calendar, another benefit that Harris and Schwarzenegger enjoyed was avoiding a contentious partisan primary.

“That’s something that would have been difficult for Schwarzenegger,” said Rob Stutzman, a Republican strategist who served as one of his spokesmen during the recall campaign.

Schwarzenegger — a strong environmentalist with a laissez-faire attitude on social issues — stood well to the left of the California Republican base. The year before the 2003 recall, GOP primary voters handily rejected a similar moderate, former Los Angeles Mayor Richard Riordan, in favor of a much more conservative nominee, the bumbling Bill Simon Jr.

“The big advantage [Harris] has, and that Arnold had, was heading straight to the general election,” Stutzman said. “Bypassing the primary allowed each to build a bigger, broader coalition in the middle, rather than on the fringe.”

Harris did, in fact, run to the left in her failed 2020 presidential bid and some of the positions she staked in that Democratic primary — on energy, immigration, healthcare — have become an issue in the current campaign, when many are just getting to know the vice president.

If there’s a disadvantage to this abridged election, Stutzman said, it’s the limited time Harris has to introduce herself. Polls have consistently shown independent and other undecided voters holding back and saying they need to know more about her and where she stands.

For that reason, Stutzman believes it would behoove Harris to open herself up to more interactions with the media, especially since she’s much improved from her stumbling early days as vice president.

Stutzman cited her jokey appearance last week alongside Oprah Winfrey when Harris let slip — was it really accidental? — that she keeps a gun at home and if an intruder breaks in “they’re getting shot.”

“It was a super-savvy move … from a campaign running hard to the middle,” Stutzman said.

Harris has enjoyed great good fortune in her hurry-up run for president.

Among other assets, she inherited Biden’s well-honed reelection team, buttressed by several Obama campaign veterans, which spared her the drama and trauma that racked Harris’ last faction-ridden bid for the White House.

But Richie Ross, another veteran of the recall election, said not to discount the months and years of Democratic strategizing that preceded her entry into the race, or the skills Harris has shown as Biden’s replacement.

“There’s nothing truncated about her preparation and nothing truncated about a lot of people working really hard to crack the code,” said Ross, who ran Cruz Bustamante’s candidacy in 2003. (His message as a backstop to fellow Democrats: “ ‘No’ on the recall and ‘Yes’ on Bustamante.”

“We’re not watching lucky,” Ross said of the vice president. “We’re watching ready.”

Call it luck, skill or some combination. We’ll see if it lasts another six weeks.