Chautala's Indian National Lok Dal party was a member of the Bharatiya Janata Party (BJP)-led federal coalition government that lost power in May 2004.
However, the BJP surged ahead in late vote counting to come within striking distance of retaining power in Jharkhand. In Bihar, analysts expected a hung assembly raising the possibility of prolonged instability and federal rule in the lawless eastern state.
"A Congress government will be formed in Haryana - it's a clean sweep," said pollster Yashwant Deshmukh. Congress, which leads a federal coalition government of more than a dozen parties, will now rule 15 of India's 28 states following its victory in Haryana and in Maharashtra state in October.
An outright win in the farm state of Haryana is seen as strengthening Congress's hold over the federal coalition, where communist allies routinely pressure it on policy for the country's huge agriculture sector.
In Bihar, the ruling Rashtriya Janata Dal (RJD) party - an ally of Congress at the state and federal levels - suffered initial setbacks.
The Press Trust of India (PTI) news agency said the RJD had secured 75 seats in the 243 seat Bihar legislature, Congress had won 10 and the opposition BJP and its allies had bagged 93 seats, with independents and snaller parties accounting for the rest.
However, maverick politician Laloo Prasad Yadav - who held power in the state for 10 years and then with his wife as a proxy chief minister for the past five years - refused to accept defeat.
"My party, the RJD is the single largest party (in the legislative assembly) and with our allies we have 92 seats," he told reporters in Bihar state capital Patna.
"I will not give up and our party will stake claim to form government," said Yadav, who is also national railways minister. In the neighbouring tribal state of Jharkhand, currently controlled by the BJP, the party and its allies seemed set to retain power, leading in 36 of the assembly's 81 seats, PTI said. The Congress and its allies were leading in 26 seats.