The CPI(M) on Thursday termed as "unprecedented" the proposal to make Prime Minister Manmohan Singh a candidate for Presidential poll, saying it shows lack of principle that ties the UPA coalition.

Reacting to Mamata Banerjee-Mulayam Singh Yadav proposal to have either Singh or A P J Abdul Kalam or Somnath Chatterjee as candidate for the post, CPI(M) Polit Bureau member Brinda Karat said it was something "unprecedented" that the name of the incumbent Prime Minister was being discussed for Presidential post.

"It is really for the UPA leadership to answer this question. It is unprecedented that the name of a sitting MP should be suggested by the government's own allies," Karat said.

"It really shows the utter lack of any principles which ties this coalition. It is for the UPA leadership to respond to this," she said.

She said today there are six names, tomorrow may be three more names will come. "This is not a game of names," she said.