PROTEST leader Suthep Thaugsuban left the Government House precinct disappointed tonight and later called his leadership group from every province of Thailand to a summit tomorrow that could determine the nation's immediate future.

Joining them will be professional groups and student university organisations in favor of speedy reform. Khun Suthep is insisting on speed now. He also wants as many government workers as possible to join the Bangkok street protest.

Khun Suthep had hoped that the caretaker leader of the Senate, Chaiyot Punyawai, would answer his call to appoint a neutral Prime Minister today.

Instead, Khun Chaiyot opted to give the caretaker Government more time to offer their possible solutions to the stalemate that has paralysed Thailand.

So Khun Suthep, frustrated and with his followers dwindling after six months of protesting, walked out of Government House and tonight made a television appeal for his key supporters to attend tomorrow's summit.

Although Khun Chaiyot earlier in the Senate admitted the previous government had been corrupt and the caretaker PM seemed to have little power except to warm the chair for someone else, he called for more time to give the other side a chance to be heard.

Most of the submissions to Senators this week about Thailand's future have come from the Yellow side of politics.

Khun Suthep was not satisfied with the call for caretaker ministers to appear before the Senate ''as soon as possible,'' wanting instead an immediate deadline.

''How long will we have to wait for a solution? How much pain must we endure with grenades and guns? If you cannot do it, we will have to do it ourselves.''

With Khun Suthep's patience exhausted and probably matched by everyone who wants the confrontation to end, Saturday afternoon's meeting could be the next significant step in determining whether Thailand faces civil war or a sensible solution.