The army in crisis-hit Venezuela has to choose whether it is "with the constitution or with (President Nicolas) Maduro," opposition leader Henrique Capriles said Tuesday.

He made the declaration to journalists after Maduro decreed a state of emergency broadening the powers of soldiers and police -- and a day before opposition-led marches demanding a referendum to oust the president.

There was no sign however of faltering loyalty to Maduro in the military, from which his late predecessor Hugo Chavez hailed.

On Wednesday, opposition protesters across the country are to demand that authorities validate a petition calling for a recall referendum against Maduro.

The opposition says electoral officials are stalling on the process. Last week, a similar march in Caracas was stopped by riot police firing tear gas.

"I say to the armed forces: the moment of truth has arrived -- to decide whether they are with the constitution or with Maduro," Capriles told a news conference.

"That is a decision for the military," he said.