Excerpts about his father from Vice President Joe Biden’s book, “Promises to Keep.”

Well count me among the shocked. In a blog post Monday morning, I warned Joe Biden fans against getting their hopes up just because he won South Carolina big on Saturday.

I saw Bernie Sanders as poised to build an insurmountable lead Super Tuesday based on the latest polls from the 14 states and American Samoa with primaries.

Instead, Biden surged and Sanders came out of Super Tuesday trailing him by 64 delegates – based on the latest New York Times count – even though Sanders won the big prize, California, which awards 415 delegates.

I issued my warning based on the latest polls available, which had Sanders leading in eight of the 14 states, Biden up in two and favored in two with no polling; and Mike Bloomberg and Amy Klobuchar up in one each.

So what happened?

Well, for one, polls don’t predict the future.

Polls only take snapshots of the days the pollsters ask the questions.

I actually sort of warned about that in my original blog post. I wrote: “A word of caution about the polling: most of it happened before Biden won South Carolina. His victory there could shuffle things around tomorrow.”

I just didn’t believe Biden’s South Carolina victory would “shuffle things around” so much.

For example:

Data for Progress, a Democratic-leaning pollster, had Sanders up 9 points in Virginia in a poll that ended Tuesday, Feb. 25.

Biden beat Sanders in Virginia by 30 points, according to The New York Times.

—A Boston Globe poll in Massachusetts had Sanders beating Elizabeth Warren by 2 points and Biden by 13. The poll ended Saturday, the day of the South Carolina primary. Biden won Massachusetts by 7 points.

— A Talk Business/Hendrix College poll in Arkansas had Bloomberg up on Biden by 1 point and Sanders by 4 as of Feb. 7. Biden beat Sanders by 19 points and Bloomberg by 24.

Data for Progress had Sanders up 9 points on Biden in Maine in a poll that ended  Monday. Biden leads in Maine by a single point.

Except for Maine, each poll ended before the South Carolina results were in.

As reported over and over last night, voters who decided late broke big for Biden.

That’s a danger in primary voting. Primary voters, who pay more attention than less politically oriented voters, often make up their minds at the last minute. That can make pollsters look bad.

A couple of other factors mattered, too.

A Star-Tribune/Mason-Dixon poll had Klobuchar up on Sanders 29-23 as of Feb. 20 with Biden only at 8 points. That might have stayed that way, but Klobuchar dropped out Monday and immediately endorsed Biden. Biden beat Sanders by 9 points.

(I’m betting Biden picks Klobuchar as his running mate if he wins the nomination.)

Pre-Tuesday polling also had Sanders up in California by 12 to 19 points, but he’s only up 9 points right now, though a lot of that vote remains uncounted.

Clearly, South Carolina influenced a lot of Californians, too. Sanders expected to win by massive margins there, giving him most of the delegates, but it didn’t happen.

In case, you’re thinking the pollsters were wrong, well, not every pollster. Two polls that came out Monday afternoon after I wrote my blog post had Biden up 15 and 20 points in Virginia. Another Monday afternoon poll release showed Biden up in Arkansas by 13 points.

That just underscores how late deciders broke for Biden.

Biden has 404 delegates, Sanders, 340 as of about 11 a.m. today, according to the New York Times.

With Bloomberg dropping out today and endorsing him, the electoral math now favors Biden.

By the way, you can clearly tell who President Donald Trump wants to face. He tweeted today about how bad Elizabeth Warren is for sticking around because she’s hurting Sanders’ chances.

The president wants to no part of the guy from Scranton.