Suthep Thaugsuban has vowed to disrupt future elections so long as political reforms have not been implemented.
The secretary general of the anti-government People's Democratic Reform Committee (PDRC) said on Bangkok's Silom stage on Friday night the PDRC was happy with the Constitution Court's ruling on Friday to void the Feb 2, 2014 election, calling it a "people's victory".
He said the Election Commission (EC) had asked the government to delay the polls several times, to no avail.
The former deputy prime minister also quoted EC chairman Supachai Somchaoren's latest comments that the next election would have to be acceptable to all sides so it would not be opposed.
Mr Suthep said if a new election was called without political reforms being implemented first, the PDRC would work harder to disrupt it and would do everything to render it void each and every time.
He insisted people were not ready for a new election and that political reforms had to be completed first
"New polls can only be held under new rules," he said.
The former Democrat Party secretary general also urged the government to take responsibility for the Feb 2 election cost of 3.8 billion baht.
He claimed the government had pushed it, lending a deaf ear to the warnings of the EC and the Auditor General's Office about the looming obstacles.
In response to Jatuporn Prompan, the new leader of the National United Front of Democracy Against Dictatorship or the red shirts, who had asked Mr Suthep to reveal the name of the "neutral" prime minister, Mr Suthep said he already had one in mind but would disclose it only after the Thaksin regime was eradicated.
He reiterated that all the PDRC wanted was for caretaker Prime Minister Yingluck Shinawatra to step down immediately.
He also said he was consulting the people about another big rally in the capital to campaign for reforms, the details of which would be known in a few days.