Earlier last week Garcia proposed a nationwide poll on capital punishment to be applied for terrorists.
Congress rejects plans
"It is saddening that while 80 per cent of the population support this measure, those who call themselves its representatives are ... trying to undemocratically block the will of the Peruvian people"
Alan Garcia President of Peru
On Wednesday, Peru's congress voted down a Garcia bill that would have added the death penalty for terrorists to the penal code.
Capital punishment for terrorists is permitted under Peru's 1993 constitution. But the penal code does not allow it under any circumstance.
The next day, after the first defeat for his 5-month-old government in congress, Garcia proposed holding a referendum to introduce executions for terrorists, but Justice Minister Maria Zavala said the idea clashed with the country's constitution.
Now Garcia wants to amend the constitution.
Critics attack 'populist' president
Critics have called Garcia's death penalty drive "populist" and harmful to Peru's international image.
But Peruvians broadly support the idea. Many still have painful memories of deadly bombings and raids by Maoist rebels between 1980 and 1998. Several thousand leftist rebels have been sentenced to long prison terms for terrorism.
"It is saddening that while 80 per cent of the population support this measure, those who call themselves its representatives are ... trying to undemocratically block the will of the Peruvian people," Garcia's statement said.
Lourdes Flores, head of the opposition National Unity alliance, called Garcia's drive "autocratic."
"He says: 'I'm the president and everybody follows me. My word is the law.' Peru doesn't have to follow his caprice. This is autocracy," she told a local radio.
Congress has to approve a referendum, a move that analysts say is unlikely. Even if Garcia achieves this other juridical hitches may stand in his way.