The Conservatives are investigating comments by one of their senior Welsh politicians who compared rioting in the US Congress to people who backed a second referendum on Brexit.
Andrew RT Davies faced calls to retract tweets aimed at Labour leader Sir Keir Starmer and Senedd member Alun Davies.
It follows the storming of the Capitol in Washington DC by pro-Trump rioters, halting debate in the House and Senate.
The Tory politician later tweeted that "violence must never be tolerated".
Labour is demanding that Mr Davies be suspended and barred from standing as a Conservative in this year's Welsh Parliament election.
The Capitol was breached by the rioters as federal lawmakers met to confirm President-elect Joe Biden's win in the 2020 US election.
The joint session of Congress was suspended and forced into recess, but later reconvened to certify the Democrat victory.
Responding to a tweet from Sir Keir, the former Tory Senedd group leader said: "To be honest I'm not sure you're in the strongest position right now given you campaigned to overturn democracy and the will of the British people."
Mr Davies, now the Welsh Conservatives' health spokesman, made the remarks about the Labour leader in response to Sir Keir saying the rioting was a "direct attack on democracy".
Allow Twitter content?
The Tory member of the Senedd (MS) responded to Labour's Blaenau Gwent MS Alun Davies in a tweet, saying: "The scenes in Washington are a disgrace as I've said and all stem from politicians - like your good self - who refuse to accept the results of democratic elections."
In a further tweet, pinned to his profile, Andrew RT Davies said: "Awful scenes in Washington DC. This is what happens when the outcome of a democratic election is not respected."
Former Conservative MP and UK minister Alistair Burt, who briefly lost the whip in 2019 over a vote against a no-deal Brexit, said it was an "appalling and completely unworthy analogy".
Mr Burt said: "Have you taken leave of your senses equating the two? If you are an office holder of any sort in the Conservative Party, resign now."
Antionette Sandbach, a former Tory MP and Welsh Assembly member who also had the Conservative whip withdrawn in 2019, replied to Mr Burt: "This is an embarrassing par for the course for Andrew and is a reflection of his thinking which he frequently demonstrated as leader of the Welsh Conservatives."
Wales' First Minister Mark Drakeford also condemned the remarks, saying there was "no excuse for using this moment to further entrench divisions in our society".
Rhondda Labour MP Chris Bryant said Mr Davies's tweet to Sir Keir was a "disgrace".
"Equating democratic political debate with an armed violent assault on the Capitol validates violence," he said.
Labour deputy leader and party chair Angela Rayner demanded Mr Davies be suspended and barred from standing for the Conservatives in May's Senedd election.
In a letter to Conservative co-chairman Amanda Milling, Ms Rayner warned the comments "risk legitimising or inciting violence in Britain and undermine our democracy and democratic processes".
Meanwhile Plaid Cymru's deputy leader Rhun ap Iorwerth called Mr Davies's comments "shameful".
"Sensible people from Starmer's party and mine - and yours, Andrew - simply condemn," he added.
What does the Conservative Party say?
A Welsh Conservative spokesperson said: 'The scenes in Washington last night were disgraceful and unacceptable. We totally condemn them. We are investigating these comments."
It is understood Ms Milling is writing to Mr Davies to remind him about the consequences of his use of language.
Mr Davies said in a later tweet: "Violence must never be tolerated and I will work with politicians of all persuasions to ensure we never see scenes like those in Washington in this country.
"No one should be in any doubt about my position on this."