Donald Trump has been accused of deserting the anti-abortion movement as he seeks to negate attacks by Kamala Harris over one of the most polarizing issues of the US election.

The Republican nominee brags often about his role in overturning the constitutional right to abortion in the United States.

But -- under relentless fire from Harris and the Democratic Party, and with a majority of Americans supporting access to the procedure -- the former president is now risking the ire of his right-wing base by claiming to promote "reproductive rights."

"Trump's abandonment of Pro-Lifers is complete," said a headline in the conservative National Review last week.

Jeremy Boreing, the co-founder of right-wing website The Daily Wire, attacked the former president as "philosophically malleable."

"His first term was perhaps the most pro-life in actual effect of any administration in our history. That is his legacy -- if he will keep it," Boreing said on X.

The backlash came after Trump took to his Truth Social platform last week to target Democrats, who had for days been attacking him over abortion at their national convention in Chicago.

"My Administration will be great for women and their reproductive rights," he wrote, hours after Harris accused him and the Republican Party of being "out of their minds" as she used her convention speech to criticize their abortion stance.

Trump's post was "the worst statement Donald Trump has made" since he launched his campaign for president in 2015, Boreing said.

It was "hard to interpret in any other way than as an affirmatively pro-choice statement," wrote Philip Klein, editor of the National Review Online, referring to abortion rights.

"By the common usage of the term, if you support reproductive rights it means you want broader access to abortion."