The historic right of the monarch's first-born son to inherit the crown have been challenged by a Beds MP.
MP Jonathan Sayeed is proposing changes to monarchy
Jonathan Sayeed said other children of the monarch, including daughters, should be considered as successors.
The monarch should also be forced to step down at the age of 75, the Tory MP told Parliament on Tuesday.
"An unwilling monarch is more likely to be an unfit monarch...Not all want to follow in their parents footsteps," Mr Sayeed said.
The comments were made during a debate on the Succession to the Crown and Retirement of the Sovereign Bill.
"I am a strong supporter of the monarch," Mr Sayeed said.
But, he added: "The danger is that without such evolution, the continued existence of a hereditary, unreformed apex in a model state will be pilloried as incongruous and used to promote Republican views."
Tory MP Sir Patrick Cormack attacked the proposals as "absurd" and "claptrap".
The Queen, who is 78, would have been ejected under the proposals, he said.
"We believe that people can indeed serve extremely well beyond the age of 75," Mr Cormack said.