Maduro is fighting on several fronts, including a stagnant economy, a dearth of foreign exchange, rising food import bills and unchecked crime rates. The former protege of late President Hugo Chavez, who died of cancer in March, is finding it difficult to keep old Chavez loyalists in line, analysts said.
Media reports alleged some of the old guard, including retired military leaders, considered using violence to unseat Maduro and claimed such action would be justified and would not be a coup.
Maduro is accused by his critics of steering Venezuela toward one disaster after another and continuing discredited policies of Chavez.
Maduro's latest crackdown on corruption received mixed results. In the most high-profile government action the mayor of Venezuela's third-largest city in the Carabobo state was arrested on corruption-related charges.
The arrest was notable because Valencia Mayor Edgardo Parra is a member of the ruling United Socialist Party of Venezuela, and not an opposition activist. The opposition isn't convinced and suspects the campaign is related to a Dec. 8 local election that could prove to be an indicator of political discontent in the country.
About 278 people were detained in other alleged corruption cases and police announced investigation into high-profile thefts of state funds.
"We, Venezuelans, are not only going to choose mayors and town councilors, but also face, through the electoral process, the crisis the country is going through," opposition leader Henrique Capriles Radonski said.
Opposition critics cited Maduro's pleas to the National Assembly to grant him new executive authority, including wide decree powers, to deal with the country's problems. Opposition critics say those new powers will be used to target their rank and file.
After Parra's arrest, state governor Francisco Ameliach, also from the ruling Socialist Party, declared: "We will not protect anyone who commits a crime involving public funds, which are sacred because it's the people's money There are no untouchables here."
Analysts said the arrest of Parra rather than a high-profile opposition politician could be aimed at winning National Assembly approval of Maduro's request for emergency powers to deal with corruption and other issues.
Capriles called Maduro's call for decree powers "shameful" and a "political pantomime."
"How dare you tell us you'll fight corruption, when the people guilty of stealing public funds are exactly the same ones you chose to govern with you?" Capriles said in published comments.
Opposition critics say Maduro, if granted decree powers, would likely use them against political foes.