The head of megachurch First Baptist Dallas, Jeffress, who is also a member of Donald Trump's evangelical advisory board, made the comments on radio presenter Todd Starnes' show.
"Let me say this as charitably as I can," Jeffress said.
"These 'Never Trump' evangelicals are morons. They are absolutely spineless morons, and they cannot admit that they were wrong."
His strong words followed a conversation about abortion.
"This is an issue of life and death," Jeffress continued.
"This is so black and white, so much about good versus evil. I don't get it.
"It really goes to the core of who we are as a country and what kind of a country we have in the future, and if we can't get this issue of life right, I just don't know where we're going to go down the road."
Mr Trump has been very vocal about his pro-life stance.
White House deputy press secretary Judd Deere confirmed that the president had recently met with Democratic New York governor Andrew Cuomo for a wide-ranging conversation on several topics of disagreement, including abortion.
According to Deere's statement, "The President raised his concerns to Governor Cuomo about Democrats' support of late term abortions" during the meeting.
Last month, New York State passed a law protecting women's access to abortion if Roe v Wade is ever overturned.
The Reproductive Health Act allows for abortions after 24 weeks if an authorised health care practitioner determines that "the abortion is necessary to protect the patient's life or health" or if "there is an absence of foetal viability".
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