The outbreak comes as the Prince of Wales reveals in a new documentary that he will stop talking about matters that care deeply after he becomes king.
However, the anti-royal campaign of the Republic said it had already spoken too much as a heir to the throne, and its attempts to influence government policy were a step too far.
The Republic said: "The royal PR car is facing a crisis as Carol prepares to take the throne."
The organization added: "Charles has commonly abused his position of power, lobbying cabinet ministers and influencing government policy with his own political agenda.
"It is not surprising that the kings are rushing to change Charles's public image as he prepares to become king, but do we really expect to believe that he will not capitalize on all the powers he is about to inherit?
"King Charles is just around the corner and we should have a widespread national debate about the future of our country, not a implicit incorporation."
The Prince has been vocal in his efforts to help protect the environment, as well as to protect endangered species and genetically modified crops.
Prince Charles faced allegations of mixing for much of his life as Britain's longest heir, who ever served the heir to the throne.
However, a former cabinet minister said he does not expect the monarchs to have no vision.
Lord Hain, who served as Secretary of State for Wales, Northern Ireland, and for work and pensions in the offices of Tony Blair and Gordon Brown, said he often spoke to Prince Charles and "welcomed" these talks.
He said, "I have never been a monarchist, but if you believe in a monarchy, then I do not see why the current monarch or the future monarch should expect to be completely devoid of vision and shut everything down."
Asked if he thought it was a shame that Charles said he would not talk about matters, Lord Hain said, "No. I respect his point of view, as we respected our dialogues when we were in government."
"When I was Minister of the Cabinet, I had regular interactions with the Prince of Wales and I greeted them.
"For the most part, I have agreed and made very valuable and interesting suggestions on housing, the environment, the need for complementary medicine to run alongside and be interchangeable with conventional medicine within the National Health Service.
"I agreed with all these things, especially with the latter, where I was in a minority.
"I did not agree with hunting dogs, but that's good.
"So I never had a problem with this, and I think the British audience … I think there is a different relationship with the monarchy now.
"I do not think we expect the monarchy to be silent or to have no vision.
"We have always found the Queen extremely well informed whenever we have been discussing, for example, Northern Ireland with her or Wales as State Secretary."
In an hour-long documentary to celebrate Prince's 70th anniversary, which will be broadcast on BBC One tonight, he confirmed that he would stop doing the same interventions he had in the past.
Prince Charles said, "If you are stirring to worry about the inner cities as I did 40 years ago, then if I mix, I'm proud of it."
"I think it is vital to remember that there is only room for a sovereign at a time, not for two.
"So you can not be the same as the sovereign if you are the prince of Wales or the heir.
"But the idea, in a way, that I will continue the same thing if I have to succeed is totally stupid, because the two – the two situations – are completely different."
Asked if he would continue the campaign, the prince said, "No, it will not be, I'm not stupid.
"I realize it is a separate exercise that is sovereign, so I fully understand how this should work."
Prince, son and heir: Charles at 70, broadcast on BBC One Thursday, November 8, at 21:00.