Himachal Pradesh Chief Minister Virbhadra Singh on Sunday said BJP leader Prem Kumar Dhumal has failed as leader of opposition."Dhumal has failed to shoulder his responsibility as leader of opposition in the Vidhan Sabha (state assembly)," Singh said in a statement.The chief minister's reaction came after two-time former chief minister Dhumal said Virbhadra Singh was treating his opponents as enemies.However, Virbhadra Singh said: "In my long political career, I have never treated my opponents as my enemy."Advising Dhumal to self-introspect before levelling baseless allegations against his opponents, he said Dhumal, during his tenure, had treated the opposition with contempt and disregard Dhumal even went a step further to the extent of filing false and frivolous cases against his political opponents, the chief minister said.