Mr Tandja's plans have drawn protests in Niger and beyond
Niger will elect a new parliament on 20 October, officials have announced, amid unrest over a new constitution giving new powers to President Mamadou Tandja.
Opposition groups have indicated they will boycott any poll, after Mr Tandja adopted a new constitution allowing him to seek a third term in office.
The president officially adopted the constitution earlier this week.
He dissolved the country's top court and parliament as he pushed through his plans to overhaul the system.
The 71-year-old was supposed to stand down in December after serving two terms in office.
He won a controversial referendum on the question last month.
Mr Tandja says he needs to stay in power to complete huge economic projects he has begun.
His backers say he has brought development and stability to Niger, one of the world's poorest countries.
But critics have accused him of carrying out a coup d'etat and label him a classic strongman.
As well as huge internal opposition, Mr Tandja's actions have also dismayed Western governments.
France, the US and the EU have all criticised his actions and encouraged him to restore democratic rule.
Some aid payments have been suspended.