Buchanan has not appeared on the network since October when he began promoting "Suicide of a Superpower: Will America Survive to 2025?" in which he laments the shrinking of the "European and Christian core of our country."
"My days as a political analyst at MSNBC have come to an end," Buchanan said Thursday in a post on the Web site of The American Conservative magazine, which he co-founded. "After 10 enjoyable years, I am departing, after an incessant clamor from the left that to permit me continued access to the microphones of MSNBC would be an outrage against decency, and dangerous."
Liberal groups had pressured MSNBC to sanction or fire Buchanan for a number of statements in the book, The New York Times reported.
Buchanan criticized Abraham Foxman of the Anti-Defamation League.
"What Foxman and ADL are about in demanding that my voice be silenced is, in the Jeffersonian sense, intrinsically un-American."
"Consider what it is these people are saying," Buchanan wrote in his blog post. "They are saying that a respected publisher, St. Martin's, colluded with me to produce a racist, homophobic, anti-Semitic book, and CNN, Fox News, C-SPAN, Fox Business News and the 150 radio shows on which I appeared failed to detect its evil and helped to promote a moral atrocity."
Buchanan, who ran twice for the Republican nomination for president, said his departure from MSNBC "represents an undeniable victory for the blacklisters."
MSNBC President Phil Griffin last month said Buchanan's future on the network was in question. "The ideas he put forth aren't really appropriate for national dialogue, much less the dialogue on MSNBC," Griffin told The New York Times.