India's communists and other opposition parties have launched a joint campaign against the government over rising prices and a nuclear deal with the US, reports BBC.
The new group contains four left-wing former government allies and a regional leader tipped as a possible future PM.
On Tuesday, the government won a vote of confidence over the nuclear deal, amid allegations of vote buying.
The vote came after the government's left-wing allies withdrew their support in protest at the controversial accord.
If the government had lost the vote, India would have faced early elections and the nuclear deal would have been in doubt.
Correspondents say the confidence vote debate has been used by many politicians to kick off campaigns for general elections due in the first half of next year.
"All the political parties present decided to launch a joint national level campaign on pressing issues before the people," Prakash Karat, general secretary of the Communist Party of India (Marxist) or CPI(M), told a press conference in the capital, Delhi.
The new group says it will campaign on the issues of inflation, the India-US nuclear deal and farmer suicides.
It consists of four left-wing parties - all former allies of the Congress party - and six other regional parties.
The most prominent among the regional groups is the Bahujan Samaj Party (BSP) led by Ms Mayawati, chief minister of India's most populous and politically influential state, Uttar Pradesh.
Ms Mayawati is a Dalit (formerly untouchable in the Hindu caste system) icon who openly talks about her ambition to become prime minister soon.
In the last few days of hectic political activity several new alignments have been formed. Ms Mayawati has emerged as one of the most important political leaders to watch in the days to come.
