UP assembly Speaker Keshari Nath Tripathi — who has been nominated as BJP candidate from Machhlishahar Lok Sabha constituency — is unlikely to oblige his detractors by resigning from his post.When reached at Allahabad from here today, Tripathi was non-committal on the issue. He said: ‘‘I will take a decision at an appropriate time.’’ He went on to say: ‘‘The question is whether or not Assembly Speakers have resigned their posts before contesting for Lok Sabha in the past.’’Tripathi continues to be the Speaker even though BJP has moved from the treasury benches to the Opposition in UP Assembly. So far, Chief Minister Mulayam Singh Yadav has shown no inclination to remove him even at the cost of attracting allegations that he is in league with BJP.Within the BJP and for Human Resources Development Minister Murli Manohar Joshi, Tripathi’s nomination is bad news — both have been arch rivals in the local politics of Allahabad. Joshi — given his long innings and pre-eminence at the Centre — has always had an upper hand, but Tripathi too has been a survivor. For this, he has had tacit patronage of both former CM Kalyan Singh and former state president Kalraj Mishra.