By Sanjoy Majumder
BBC News, Delhi
The results of elections in four Indian states and the union territory of Pondicherry have come as a huge boost for the country's communist parties.
Joy for communists - but how left-wing are they??
An alliance led by the country's main Communist party, the CPI(M) has returned to power for a record seventh straight term in the eastern state of West Bengal.
In the southern state of Kerala, the CPI(M) led-Left Democratic Front has wrested power from the governing Congress Party.
Once pushed to the margins of Indian politics the communists are now an influential player especially at the federal level where, with some 60 seats in parliament, they hold the key to the Congress-led ruling coalition.
Not surprisingly, Communist leaders are upbeat about their future.
"Overall these results have strengthened the role of the left in national politics," said Prakash Karat, the top leader of the CPI(M), at a news conference shortly after the election results came in.
Despite supporting Congress at the federal level, they oppose the party at the state level leading to an uneasy political equation.
With their triumph in West Bengal and Kerala, they can exert even greater influence on the federal government, especially on economic policy.
The communists have at times made life difficult for Prime Minister Manmohan Singh, opposing him on a number of issues including increased foreign investment, privatisation and the country's growing ties with the United States.
There is little doubt that they will continue to do so.
"We will continue to follow our agenda," says Mr Karat.
The communist victories could not be described as entirely unexpected as West Bengal and Kerala are historical strongholds.
Buddhadeb Bhattacharya has delighted business leaders
Many opposed to them see a silver lining in West Bengal where they were led by the state's popular chief minister, Buddhadeb Bhattacharya.
Taking a cue from China, Mr Bhattacharya has pushed through an ambitious economic reforms programme with an approach more capitalist than communist.
He has invited foreign investment, privatised state-owned companies and properties and is pushing to make West Bengal a major IT hub - moves that have often earned him the ire of his party's politburo members.
Indian business leaders have openly expressed their admiration for the chain-smoking and austere Mr Bhattacharya, saying that they hoped his party bosses could emulate his pragmatic approach.
But even as Mr Bhattacharya is basking in his triumph in Bengal, the victory of the communists in Kerala is being attributed to a hardline octogenarian leader, VS Achuthanandan.
Mr Achuthanandan was brought into the campaign at the last minute, despite opposition by party liberals and is seen as the architect of the victory and quite likely the next chief minister of the state.
But he also represents the more traditional, hardline wing of the party - dominated by ageing leaders often seen as out of sync with India's growing reputation as an economic power.
Despite the communist victories, India's governing Congress Party will not be too unhappy with its performance.
Sonia Gandhi's victory has boosted her Congress party
Congress is well placed in the north-eastern state of Assam, where it is likely to return to power with the help of a coalition partner.
In Tamil Nadu, the party has made its most impressive showing in decades enabling it to be a junior partner of the regional DMK party.
The DMK is also one of their federal coalition partners which balances the power equation.
But the party will be most buoyed by the massive victory of its party president, the Italian-born Sonia Gandhi.
Mrs Gandhi was returned from the parliamentary constituency of Rae Bareilly by a margin of over 400,000 votes over her nearest rival.
She quit parliament in March, following a controversy over her role as head of the National Advisory Council, a state-funded body set up to advise the current government.
Under Indian law, MPs may not gain financially from other public posts.
But now her victory is being seen as a vindication of her stand.
Rae Bareilly is located in the politically influential state of Uttar Pradesh - once a Congress stronghold the party has lost its position to regional, socialist parties.
The party is desperate to regain its presence in the state and many in Congress are hoping that Mrs Gandhi's victory will spark off a trend.
More significantly, her campaign was handled by her children, Rahul and Priyanka Gandhi.
With her massive victory, there are already calls for them to take a more active role in rebuilding the party in the state.
Congress is hoping that the magic of the Gandhi name can deliver rich political dividends once again.