"What has happened to our ally BJP. Has it been afflicted with an illness or has it been beset with internal squabbles," Thackeray said in an editorial in party mouthpiece 'Saamana' today.
Advani's musings were demoralising, Thackeray said and asked NDA "not to lose heart".
"If Advani has any doubts, he can come to me and I will give him a dose of morale and strength," Thackeray said commenting on his blog where he predicted a non-Congress, non-NDA alliance coming to power.
"This is like a general saying before a war that there is no guarantee on the outcome, and demoralising the entire army," Thackeray said.
He asked the NDA to prepare for the general elections with renewed vigour.
The issue of contenders for the Prime Minister's post within the NDA -- Bihar Chief Minister Nitish Kumar and Gujarat Chief Minister Narendra Modi -- could be sorted out after the elections, he said.
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Writing in his blog, Advani had ruled out formation of a government headed by the Third Front but said that a non- Congress, non-BJP Prime Minister heading a government supported by one of these two parties is possible.
"The blog has put BJP in a quandary," Thackeray said.
Thackeray said the next Prime Minister should be from the NDA and that decision could be taken after polls are over.
"No point conceding defeat now, without even entering the boxing ring.
"Even Advani himself has been a Prime Ministerial contender over the years and if there is consensus, his wish can also be fulfilled," Thackeray said.
The blog would add fuel ambitions in Nitish Kumar and Narendra Modi for the prime minister's post, he said.
Shiv Sena would play "free-style wrestling" in attempting to overthrow Congress from power, Thackeray said.
The saffron flag will fly atop Delhi's Red Fort in 2014 polls, he said.