Kriengkrai Thiennukul, vice chairman, said that the survey covering all 42 industry groups would be wrapped up next week.
He said that orders in the 2-month period are usually the highest in a year.
"While foreign buyers cut down orders, orders from domestic companies have also fallen. Political tension has killed the consumption appetite, affecting business operators in all sectors," he said.
During the 2011 flood, foreign buyers experienced difficulties, as local producers could not deliver the ordered products. Political tension has furthered eroded their confidence in Thailand and some have shifted orders to other countries, he said.
Meanwhile, he was also concerned with the investment outlook. At present, the Board of Investment has difficulties in approving large-scale projects. If the new government could not be formed soon and conflicts continue, foreign investors could turn to other countries.