Thousands ignored heavy rain to march in Ecuador's capital to protest against constitutional changes that would allow indefinite re-election of the president and other officials.
They also demonstrated against legislation to alter labour and land ownership rules.
The march in Quito organised by indigenous communities, unions and student groups was largely peacefully, though small bands of activists clashed with police after the demonstration.
President Rafael Correa, an economist who identifies himself as a follower of 21st century socialism, is pushing a package of constitutional changes that would end term limits for all elected officials.
Passage is considered likely because his Alianza Pais party holds 100 of the National Assembly's 137 seats.
Mr Correa, who was first elected in 2006 and would have to leave office in 2017 without the change, has said he would seek another term only if he felt his "revolution" was threatened.
He is popular among Ecuadoreans for his government's generous social spending but is widely criticised for intolerance of dissent.