Shukla, not holding any political post with the saffron outfit, is likely to join the BJP, a source close to him said.
He was believed to have fallen out with Sena president Uddhav Thackeray of late.
Shukla e-mailed his resignation this afternoon to Uddhav, the Editor and Chief Trustee of 'Prabodhan Prakashan', the publisher of the tabloid.
Shukla, who started his career with 'Nirbhay Pathik', joined 'Dophar ka Saamna' as chief reporter in 1993 before quitting in 1998. He was appointed as Editor by Uddhav in 2005, after his predecessor Sanjay Nirupam quit.
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Shukla was the party's face for putting forth its view on various issues before print as well as electronic media.
He of late stopped participating in television debates, reportedly at the behest of Uddhav as the latter believed that Shukla was siding with the BJP.
However, the source denied this contention.
BJP and Shiv Sena share power both at the Centre and state government.