"I have done lots of campaigning for Bernie, his causes, and the messaging his campaign staff has either emailed or contacted me directly on," Chong wrote on Twitter, adding minutes later: "After months of support and endorsement videos, I have to report that Bernie Sanders pulled away his invite to me."
"Hey just heard that there was a scheduling conflict with the Bernie Sanders rally!" he tweeted. "Hope to continue my support, reschedule, and continue activism, political change and promoting peace anywhere possible."
"There is one candidate who stands head and shoulders above them all who has weathered many storms and is totally ready to be the commander in chief, or the commander in kush, as I like to say," Chong said at the time.
Though Sanders has pushed for an end to the federal ban on recreational marijuana use, which would leave the question to the states, he has stopped shy of backing full legalization.
Chong and co-star Cheech Marin, better known as "Cheech and Chong," became stars with their seminal 1978 stoner film "Up in Smoke."
They parted ways a few years later, as Marin sought more mainstream work, but Chong's dedication to marijuana -- in particular, legalizing it -- has remained strong for decades. (Including a nine-month stint in prison for selling bongs and pipes online.)
His attachment to Sanders, whom he admiringly described to CNN in January as being "like the best kind of weed you can get, because he's the answer to all our problems," seems to be at risk of burning out a little faster.
The Sanders campaign didn't immediately respond to a request for comment on the alleged snub.