The ruling Bharatiya Janata Party (BJP) of Prime Minister Narendra Modi is continuing the drive to win over rural India, wooing farmers in the southern state of Karnataka as campaigning began for state assembly elections.

The BJP is aiming to oust the opposition Congress party which currently rules the state.

Kicking off the campaign on Feb 4 at a rally in the state capital Bengaluru, Mr Modi said farmers were the "TOP" priority for the BJP. He spelt out "TOP" as tomato, onion and potato.

"Congress is standing at the exit gate in Karnataka," he said, while outlining the initiatives his government has planned for farmers.

Congress president Rahul Gandhi countered at a party rally in the state yesterday by accusing Mr Modi of failing to help farmers and criticising him for not waiving loans to them.

The recent federal budget included spending of 14.34 trillion rupees (S$297 billion) on agriculture and the building of rural roads and homes. The government has promised to build a 160km-long suburban railway network in Bengaluru, which is often dubbed India's IT capital.

Mr Modi is expected to address half a dozen more rallies in Karnataka as his party makes a determined push to expand its presence to the south, where it has thus far remained relatively weak compared with the rest of the country.

Karnataka, with a population of 64 million, is one of the country's more prosperous states. The BJP was in power in the state until the 2013 election, when the Congress seized control on the back of a string of corruption scandals involving senior state leaders.

The BJP won a dismal 40 state assembly seats in the election while the Congress, led by current Chief Minister K. Siddaramaiah, romped home with 122 out of the 224 seats at stake.

Mr Siddaramaiah remains at the centre of the current Congress campaign. His face remains dominant on party posters, for example, framed by smaller pictures of newly installed party president Rahul Gandhi, as well that of his predecessor and mother Sonia Gandhi.

The election in Karnataka is crucial for the Congress, which has suffered a series of losses in state elections and is now in power in only four of the 29 states in India. Karnataka is among eight states that go to the polls this year, ahead of the general election next year.

Congress spokesman Tom Vadakan said: "A situation has risen now where every state is important. Karnataka is the largest state and the Chief Minister is very clear that he has delivered. They (BJP) are trying to create a narrative that it is Modi versus Rahul Gandhi. But it is not. We have a strong local leader.

"It is Modi versus Siddaramaiah."

Analysts said Karnataka would be a tough battle for the BJP and an even more important test for the Congress.

Dr Sandeep Shastri, a political analyst and pro-vice-chancellor of Jain University, said: "It is going to be very interesting. It reflects the competition between two narratives. The BJP, on the one hand, with a highly micromanaged campaign from Delhi and a local leadership which doesn't evoke too much confidence. On the other hand, the Congress is focusing on its own state government.

"The Congress has to retain power to reassert its position as the main opposition. For BJP, too, Karnataka is important. This is a gateway to the south," he said.

Local and caste issues will be key factors in the polls, according to analysts. The BJP is hoping to get the support of the Lingayat community, which makes up 10 to 14 per cent of the population in Karnataka. The party has fielded Mr B. S. Yeddyurappa, a former BJP chief minister and a Lingayat leader, even though he was forced to resign in 2011 midway through his term after being named in a mining scam.

The Congress is stoking regional sentiments by supporting demands within the state for a separate flag, for instance.

A state government panel last weekrecommended a separate flag in yellow, white and red for Karnataka. No other state, other than Jammu and Kashmir, has its own flag in India.

Professor Narendra Pani, of the Bengaluru-based National Institute of Advanced Studies, said: "The Congress is playing up the regional line with the demand for a state flag. This is a position usually taken by supporters of the BJP. It could eat into BJP support at some level.

"The interesting aspect of the election is that a local leader is taking on Modi," he said.

The state election is due to be held before May as the Election Commission has yet to announce dates.