Prime Minister Baburam Bhattarai called for new elections in six months but some have questioned his legitimacy and three political parties resigned, the BBC reported.
When politicians failed to meet a Sunday deadline for agreement on a new constitution, Bhattarai said there was "no alternative" but polls in November and that he would form a caretaker government.
"Though we were unable to promulgate the constitution, we have decided to seek a mandate through elections for a new Constituent Assembly on 22 November," the prime minister said in a televised address.
The Constituent Assembly was elected to a two-year term in 2008 but its term has been extended four times after political parties failed to reach agreement on a constitution.
Bhattarai called new elections instead of declaring a state of emergency, which would have allowed the Legislature to be extended six months, after a Cabinet meeting, the BBC said.
Opposition parties, however, have disputed the prime minister's authority to call elections, and three of the parties have resigned.
Political parties have failed to agree on whether states in a new federal system should be formed along ethnic lines.