Kathmandu, Jan 12 (IANS): Nepal's political parties have failed to hammer out a solution to the contentious issues concerning constitution drafting within the period provided by the Constituent Assembly, party leaders said Monday.

The Constituent Assembly Thursday gave the parties four days to forge a consensus in the hope of introducing a draft constitution by Jan 22.

But with the political parties failing to do so, the chances of bringing even the preliminary draft of a new constitution have ended, which will likely deepen the political crisis in the Himalayan country.

The parties have less than two weeks to meet the deadline but there has not been any substantial progress on key issues of the new constitution, Nepal's Constituent Assembly (CA) chairman Subash Chandra Nembang said.

The next Constituent Assembly meeting is scheduled Tuesday when a heated debate between the ruling and opposition parties is likely, according to Xinhua news agency. The ruling parties -- Nepali Congress (NC) and the Communist Party of Nepal (Unified Marxist-Leninist) [CPN-UML] -- are likely to demand a start to the process of reaching a consensus, while the opposition front -- led by the Unified Communist Party of Nepal (Maoist) -- has already blocked it.

The failure in forging a consensus is likely to increase the tension between the ruling coalition and the opposition front -- which includes the Joint Madhesi Forum.

The opposition parties have called a strike Tuesday in capital Kathmandu to press the ruling parties to accept their demands.