Democrat Party leader Abhisit Vejjajiva has backed the invocation of martial law, urging all sides to support any action which prevents loss of life and helps restore peace.
Mr Abhisit said on Tuesday said the army had responded to concerns the political conflict would escalate amid the failed enforcement of security laws.
The Democrat leader took to his Facebook page to welcome the military intervention, saying all sides should support any legal means taken to protect the public and maintain order.
He cautioned that the use of wide-ranging powers which fall under martial law must be exercised only if necessary for national security, and must not be used to reduce public freedoms for the political benefit of certain parties.
Mr Abhisit said martial law could help authorities solve pressing short-term problems. But to solve the conflict sustainably over the long term, a political resolution was essential and security forces alone could not accomplish it.
All sectors in society must have a role in solving the nation's woes, he said.
The Democrat Party will call a meeting of its executives on Wednesday to discuss the party's stance on the matter, he said.
Chartthaipattana Party adviser Somsak Prisanananthakul, meanwhile, repeated his stance that the political situation warranted military intervention.
He said martial law was the most suitable option, as it gives the army full authority to handle the situation while avoiding the more extreme option of staging a coup.
That would would have sparked opposition both internally and from the international community. He believed the situation will ease now that martial law has been declared.
Political gatherings had been banned during military interventions in the past. This time, however, authorities are allowing protest groups to continue their rallies in the capital.