With just hours to go before the GST launch, the Samajwadi Party (SP) was unsure about whether it would attend the midnight function in Delhi.
"Whether we attend the midnight GST launch or not will be known later in the day," said senior SP leader Naresh Agarwal.
The Rajya Sabha MP added categorically that his party opposes GST and would not support it.
Agarwal had yesterday termed GST a "black law" that was "similar to re-establishment of the East India Company in the country".
His colleague, senior party leader Rajendra Chaudhary, however, said SP had always been in favour of the tax reform.
The party had supported it in Parliament as well as the Vidhan Sabha, Chaudhary said when contacted.
There was some ambiguity about the Bahujan Samaj Party (BSP) as well. BSP sources said party president Mayawati had not gone to Delhi and was in the state capital. However, senior BSP leader Satish Chandra Misra was in New Delhi, sources pointed out.
Several parties, including the Congress and the Left parties, have decided to boycott the event.
Finance Minister Arun Jaitley has asked opposition parties to reconsider their decision to skip the GST launch, saying they were all consulted on the indirect tax reform and could not run away from it.
"I hope every political party will reconsider and revisit its decision on not participating in the launch event to be organised in the Central Hall of Parliament," he said.
The GST, being billed as the biggest tax reform since Independence, will subsume all indirect state and central levies, making India a single market.