The red shirts in 20 northeastern provinces are suspicious of the speed at which the court is considering the case which determines Ms Yingluck's prime minister status, according to Anutin Tinnaraj, chairman of the northeastern chapter the pro-government the United Front for Democracy Against Dictatorship.
The court said it would hand down the decision on Wednesday after a hearing a day earlier.
Personally, Mr Anutin said he felt this was orchestrated by anti-government factions seeking to install an appointed prime minister as proposed by Democrat Party leader Abhisit Vejjajiva.
The Election Commission, which on Friday said it had finished drafting the July 20 royal decree, sought to delay sending it to the government on Tuesday.
To him, it smacks of a collusion to delay the July 20 election to push Mr Abhisit's agenda.
The former prime minister on Saturday proposed a reform roadmap by asking that the July 20 election be delayed and Ms Yingluck step down so the Senate speaker could appoint an interim "neutral" prime minister to oversee reform, to be spearheaded by the People's Democratic Reform Committee (PDRC) and the Reform Now Network.
The caretaker government and the red shirts flatly ruled out the idea as unconstitutional.
They instead urge all parties to propose their reform agenda in election campaigns to let voters choose.