Pheu Thai spokesman Prompong Nopparit called Mr Suthep insincere and said he planned to use the proposed debate to be a venue to grill the caretaker premier and her government.
''Mr Suthep set up a condition on debating with Ms Yingluck to attack her and her government. The debate will be a waste of time,'' he said. Instead, the People's Democratic Reform Committee leader should start attempts to solve the conflict with a closed-door meeting with no television broadcast.
''The proposed debate will create more problems instead of finding a solution,'' he added.
Mr Suthep proposed a one-on-one meeting with the caretaker prime minister to find a way out of the political crisis, but the meeting must be televised to the public with no one else involving in the talks.