Two hundred youths on Tuesday held a demonstration outside the home of Malaysian Indian lawmaker Karpal Singh, demanding that he apologise for threatening to sue Perak state's constitutional head, Sultan Azlan Shah.
Singh wants to sue the monarch for allowing a change of government in Perak, where the opposition alliance lost majority due to defections and its chief minister was replaced last week.
Singh later said he would not back off.
Wearing yellow bandanas, the youths belonging to the ruling United Malay National Organisation carried placards and shouted slogans against Singh, who is chairman of the opposition Democratic Action Party (DAP), Star Online said.
Singh lashed out at the police for allowing the protest.
He has also hit out at the opposition alliance chief, Anwar Ibrahim, and other alliance leaders for being "inconsistent" on the question of defections and on "party-hopping" by legislators.
He has since said that he was willing to meet Ibrahim, but would also discuss the question of suing the Sultan, New Straits Times said.
His move has angered conservatives in Malaysia where the royal constitutional heads are revered.
Singh has said that he would re-consider DAP's continuing in the opposition alliance. But his other DAP colleagues are not amused. They think Singh has over-reached and over-reacted, The Star newspaper said.
The newspaper, in a commentary, said Singh may need to back off since he cannot afford to annoy his DAP and opposition alliance colleagues.
"Lawyer-cum-politician Karpal Singh has given DAP a stature of national standing as a result of his many battles for rights and democracy, both in and outside Parliament. But has he overstepped his mandate with the salvo he fired on Sunday?".