Initial reports suggested the VCK would remain part of the opposition alliance while offering external support to Vijay.Chennai:

Tamil Nadu's Viduthalai Chiruthaigal Katchi will formally exit the DMK-led alliance that chief minister Joseph Vijay's TVK thumped in the April-May election, sources told NDTV Tuesday morning. VCK boss Thol Thirumavalavan is expected to make the announcement later today.

The VCK and other DMK allies, including the Congress and the CPM, kicked up a row after choosing to back the Tamilaga Vettri Kazhagam. On its electoral debut the TVK won 108 of the state's 234 Assembly seats but fell 10 short of majority. It was the VCK's two seats - in addition to the Congress' five and more from the Left and Indian Union Muslim League - that put Vijay over the top, and ensured he became the first Tamil actor-chief minister since J Jayalalithaa.

MLAs from these parties were inducted into the new government, though of them only the IUML and Communist Party of India (Marxist) have, so far, formally left the larger party's side.

Unsurprisingly, extending the support fractured ties between these parties and the DMK, and Thirumavalavan's expected announcement will confirm a split with the MK Stalin's outfit.

Post the announcement the VCK will take part in a meeting to be hosted by the TVK. The guest list for that meeting - seen as an effort to strengthen ties - will likely include the Marumalarchi Dravida Munnetra Kazhagam - another long-standing DMK ally that has now broken off.

The MDMK's departure from the DMK fold is significant given close relations between the former's boss - Vaiko - and the Stalin family that leads the Dravida Munnetra Kazhagam.

Vaiko snapped his nine-year-long ties with the DMK last week, though he stopped short of confirming he will join the TVK-led front. He justified the exit by alleging "attempts were made to weaken" his party and spoke darkly of a "secret plan to enable the AIADMK (i.e., the All India Anna Dravida Munnetra Kazhagam, the DMK's arch-rival) to form the government".

The reference was to sensational rumours last month - when it became clear the TVK had become the largest party but didn't have majority - that the DMK could 'secretly' back the AIADMK and its ally, the Bharatiya Janata Party, to keep Vijay from forming the government.

But the MDMK's split didn't come without controversy of its own. Its two MLAs - elected on the back of support from the DMK - have indicated they will remain with the latter party. That means that even if the MDMK were to align withthe TVK, its legislative strength will not increase.