Mamadou Tandja says the people of Niger want him to stay
Niger's lawyers have called a strike, as President Mamadou Tandja begins his campaign to hold a referendum for a third term in office.
The lawyers say their action is to show solidarity with the Constitutional Court, which was dissolved after declaring Mr Tandja's plan illegal.
The president wants citizens to vote on 4 August to allow him to hold office for three more years.
The EU has delayed some aid to the uranium-rich country over the row.
The General Assembly of the Order of Lawyers said in a statement, it has decided to "lay down its robes", reports Reuters news agency.
Mr Tandja has reportedly imposed restrictions on the private press in his bid to hold the poll, despite mounting opposition at home and abroad.
The EU is the first body to impose financial sanctions on the government over Mr Tandja's efforts to remain in power, although it has also been condemned by the US and former colonial power France.
"Because of the influence this could have on the management of public finances, it has been decided to postpone the payment of a tranche of budget support," a European Commission official in Brussels told Reuters.
President Tandja's term is due to end in December. Opponents have said they fear a return to dictatorship if he stays on.
President Tandja has insisted the people of Niger want him to stay beyond the end of his second five-year term.
Last month, the constitutional court ruled that Mr Tandja, 70, was breaking his oath of office by trying to stay on.
"The president... cannot seek the amendment of the constitution without violating his oath," the judges ruled.
He has also dissolved parliament, which opposed his plans, and says he will rule by decree.
Mr Tandja was first elected in 1999, and then again five years later.
He had previously promised to quit in December this year, a month after presidential elections are due to be held.