Congress general secretary in-charge communications Jairam Ramesh also said the sanctity and autonomy of all Constitutional bodies have been badly damaged since 2014 -- the year Narendra Modi became Prime Minister.
Soni has resigned citing personal reasons before the expiry of his tenure in May 2029, official sources said on Saturday.
"His resignation is not in any way connected to controversies and allegations surrounding the Union Public Service Commission (UPSC) after probationary IAS officer Puja Khedkar issue came to the fore," they said.
Reacting to the development, Ramesh said, "The sanctity, character, autonomy, and professionalism of all Constitutional bodies have been badly damaged since 2014. But at times even the self-anointed non-biological PM is forced to say enough is enough."
He added, "Mr. Modi brought in one of his favourite 'academics' from Gujarat as a UPSC member in 2017 and made him Chairman in 2023 with a six-year term. But this so-called distinguished gentleman has now resigned five years before the expiry of his term.
"Whatever the reasons that may be given, it appears clear that he had to be nudged out given the current controversy in which the UPSC is involved." Many more such characters have populated the system, he said, and wondered why the Chairman of the NTA remains untouched so far.
"The UPSC chairman had tendered his resignation citing personal reasons over a fortnight back. It is yet to be accepted," a source said.
Eminent educationist Soni, 59, took over as a member of the Commission on June 28, 2017. He took oath as the UPSC chairman on May 16, 2023, and his term was to end on May 15, 2029.
Sources said Soni was not keen on becoming the UPSC chairman and had requested to be relieved. However, his request was not accepted then.
They said Soni has now desired to devote more time to "socio-religious activities." The development assumes significance as the UPSC on Friday said it has lodged a criminal case against Khedkar for faking her identity to fraudulently avail attempts in the civil services examination beyond eligibility and taken steps to debar her from future selections.