Labour MP Peter Dowd has claimed Theresa May isn't "backing her man", but is instead distancing herself from the plan to rise National Insurance contributions from the self-employed to 2%.
Mrs May has defended the Chancellor's provision in the Budget, saying the change would make the system "simpler, fairer and more progressive."
However, speaking to reporters at the EU summit in Brussels on Thursday, she said the changes would not be put to the vote until autumn 2017 - an announcement which has been hailed as a "partial U-turn" by shadow chancellor John McDonnell.
Dowd, MP for Bootle and the shadow chief secretary to the Treasury, told Julia Hartley-Brewer the Prime Minister was distancing herself from the hike - referencing Tammy Wynette's classic country hit Stand By Your Man in the process.
He said: "Unlike Tammy Wynette, Theresa May isn’t backing her man, she’s doing a strategic withdrawal.
“The Government have got themselves into a mess on this, they promised they wouldn’t do this [raise NI] in the manifesto.
"They did it, thought everyone wouldn’t notice and everyone did.
"It’s an own goal."