First Minister Mark Drakeford has said he cannot see how Boris Johnson can remain in office, saying a “normal” Prime Minister would resign as “a matter of honour”.
The leader of the Welsh Government said the Prime Minister had played “fast and loose with our constitution” following the Supreme Court ruling.
On Tuesday Mr Drakeford refused to explicitly call for Mr Johnson’s resignation at the beginning of the Welsh Assembly’s plenary session, but said he did not think that he could “legitimately” continue as PM.
The First Minister said: “When a prime minister is found to have acted unlawfully and undemocratically, I don’t see how that person thinks that he can legitimately continue in office.”
Earlier on Tuesday, Mr Drakeford tweeted that any “normal” prime minister should resign as a “matter of honour”.
He tweeted: “The PM tried to play fast and loose with our constitution. The unanimous decision by @UKSupremeCourt is a huge victory for the rule of law.
“Parliament was never prorogued and must now hold this Government to account.
“Any normal prime minister would – as a matter of honour – tender their resignation after such a unanimous verdict from the UK’s highest court. It is the final straw in a pitiful episode for the country.”
Plaid Cymru leader Adam Price, who had asked Mr Drakeford at the plenary to join him in calling for Mr Johnson to resign, labelled the Prime Minister a “dictator”.
Mr Price said: “Lying to the people, Parliament, and the Queen, is a trinity of grave constitutional crimes.
“What is totally clear is the UK Prime Minister had closed the doors of Parliament with the relish of the dictator that he is.”
Mr Price called Mr Johnson a “dishonest Prime Minister” in a tweet before the plenary session, and repeated calls for a People’s Vote.
He tweeted: “Only one response now acceptable by the Prime Minister to this damning (and unanimous) judgement by the Supreme Court: Resign.
“After getting rid of this dishonest Prime Minister, Parliament must now move to end the chaos and uncertainty and take it back to the people in a People’s Vote so we can finally move on from this dark chapter in our politics.”
Welsh Conservative leader Paul Davies said while his party respected the Supreme Court ruling, he blamed the “Brexit impasse” of Labour MPs in Parliament of having “frustrated the Brexit process against the will of the Welsh and British people”.