Check your inbox: Vermont U.S. Sen. Bernie Sanders is inviting you to an organizing event in “Bostob.”

The Hub has apparently been renamed by Sanders’ presidential campaign team — at least in an email sent to supporters asking them to RSVP for one of his “organizing kickoff” events on April 27.

Boston is misspelled no fewer than three times across the subject line and body of the email. In fact, the Bay State capital is never spelled correctly. A slip of the thumb perhaps, pundits say, but nonetheless a surprising gaffe from a campaign that should be functioning like a well-oiled machine.

“The Democrats’ big claim about Donald Trump is, ‘He’s crazy. He’s not capable of being president,’” said GOP strategist Patrick Griffin. “Now one thing’s for sure, Donald Trump can spell Boston.”

Griffin added that, “When you’re raising the kind of money Sanders is raising, and you have the kind of political profile, and you’ve been through this once before, you should have the nuts and bolts of campaign tactics figured out.”

Sanders’ campaign said Sunday morning the misspelling came from “information dynamically pulled from a supporter-created event page” that has now been fixed. They called it a “simple case of human error” from a supporter, not a paid campaign staffer.

Other facets of Sanders’ campaign appear to be working well. So far, the 77-year-old has out-raised his opponents, bringing in $18.2 million in just 41 days. He received nearly 900,000 individual contributions in six weeks, hitting that milestone faster than in his 2016 presidential bid. Early polls of Democratic primary voters have also put him up top, or second only to former Vice President Joe Biden.

John Cluverius, a University of Massachusetts Lowell political science professor, said the slip-up was, “more surprising coming from the Sanders campaign given how much fundraising they do, how well they are doing it, and the fact that Bernie Sanders has been in office for a while, has run campaigns before and has run for president before.”

“It sounds like something somebody wrote with their thumbs,” he said.

It’s not like Sanders’ team screwed up the spelling of a no-name town, either. Boston, Cluverius said, “has a history of progressive politics. I think there’s a lot of competition for Boston-based activists, Boston-based endorsements and Boston-based money.”

“There are people who I’m sure will be very upset with the Sanders campaign and make angry calls to them — and still go to the event and still give money and still vote for Bernie Sanders,” he said. “This is a headache for the campaign that’s going to go away, not a virus.”