The new legislation was approved after nine hours of intense debate, with the government promising to allocate $35 million to create biometric voter registration lists, a key concession to the opposition. It confirms December 6 as the date for presidential and parliamentary elections.
The president had reportedly not eaten since Thursday, and had canceled an official visit to Cuba over the standoff.
In January, Bolivians approved a new constitution allowing the president to seek a second five-year term in December's elections and giving more power to the country's indigenous majority.
The new constitution came into effect on February 7. Opposition parties believe it will give Morales, Bolivia's first indigenous president, an unfair advantage in the upcoming elections.
They demanded an updated voter registry, raised arguments over whether Bolivian expatriates should be able to vote, and contested the number of seats in Congress that should be assigned to indigenous groups.
Morales was inaugurated in January 2006 and is expected to easily win a second term in December's elections, keeping him in power until 2014.
