Votes are being counted in Venezuela after a referendum on a series of far-reaching constitutional changes sought by President Hugo Chavez.
Voters in Caracas were woken by fireworks and loud music
Turnout in the capital, Caracas, was said to be high and the vice-president said the result appears to be close.
The raft of reforms would see the end of presidential term limits and the Central Bank's autonomy removed.
Mr Chavez says the proposed changes would return power to the people, but opponents accuse him of a power grab.
Residents of Caracas were woken before dawn by fireworks and loud music, says a BBC correspondent.
It was a rallying call to vote, correspondent James Ingham says, and appeared to have the desired effect, with long queues, several hours long, forming outside polling stations.
Some polling stations stayed open late to accommodate them.
"We will accept the results whatever they are. Venezuelans have never voted so often as during these nine years of peaceful and democratic revolution," Mr Chavez said after voting.
The past weeks have seen large anti-reform protests and the defection of several Chavez allies, complaining that his reforms go too far.
Indefinite re-election of president, term increased from 6 to 7 years
Central Bank's autonomy ended
Structure of country's administrative districts reorganised
Maximum working day cut from 8 hours to 6
Voting age lowered from 18 to 16
Social security benefits extended to workers in informal sector
Mr Chavez says the package of reforms is necessary to "construct a new socialist economy".
He has proposed 33 changes, and the National Assembly, which is composed of his supporters, put forward a further 36 amendments.
Mr Chavez' opponents called for close monitoring of the ballot. Opinion polls have suggested that the result could be close, although surveys in the past have tended to underestimate the level of support Mr Chavez enjoys.
The BBC's Americas editor, Emilio San Pedro, says the elections are expected to be as free and fair as all previous ones since Mr Chavez came to power in 1998.
One proposal is to allow the president to stand for re-election an indefinite number of times.
The opposition camp has mounted a vocal campaign
Under the current constitution, Mr Chavez would have to stand down when his term expires at the end of 2012.
Other changes up for approval include giving the president control over the central bank, the creation of new provinces governed by centrally-appointed officials, and a reduction in the voting age from 18 to 16.
There are also proposals to expand presidential powers during natural disasters or political "emergencies".
On the social front, changes include establishing a maximum six-hour working day and 36-hour working week, and widening social security benefit to workers in the informal economy.
A number of defections from the president's camp have encouraged opponents, but Mr Chavez has dismissed these one-time allies as traitors.