NEW DELHI - India's embattled Congress party won big in a southern state election this weekend, exceeding expectations and gaining fresh momentum to take on entrenched Prime Minister Narendra Modi in national elections next year, top politicians and analysts said.

At the same time, they cautioned that Congress' victory on Saturday in Karnataka state, home to the booming tech hub of Bengaluru, was largely due to local factors.

The popular Modi's strongman image and Hindu polarisation strategy, they said, would likely power his ruling Bharatiya Janata Party (BJP) to victory in upcoming elections in the heartland states and nationally.

But for the beleaguered opposition party, which won fewer than 10% of the 545 seats in parliament's lower house in 2019, the win provides a foothold to re-establish itself as a political force to be reckoned with in the world's largest democracy.

"This is an opportunity for Congress to enhance state efficiencies in Karnataka, build a new governance model and showcase that to the country," said Prithvi Datta Chandra Shobhi, a political commentator who teaches at Krea University in southern India.

For the near term, however, he added: "These results have no bearing on the 2024 elections, they don't help us to predict what might happen either in Karnataka or nationally so far as Congress' chances are concerned."

Congress, which fared poorly in Saturday's municipal elections in India's most populous state of Uttar Pradesh in the north, where the BJP swept all 17 mayoral seats, next faces elections late this year in Rajasthan, Madhya Pradesh and Chhattisgarh states.

Among its many challenges: to resolve internal rivalries, market its platform of welfare economics, forge strategic alliances with India's multitude of regional parties, and counter the strong messaging power of Modi and the BJP, analysts said.

Congress ruled India for 54 of the 75 years since independence from Britain, but is now at its weakest since Modi gained power nationally in 2014.

The party has won just one state election since December 2018, crumbling under the onslaught of the BJP's Hindu nationalism, the government's generous social spending, Modi's popularity, and its own leadership vacuum.

STRONGMAN MODI

The impressive win in Karnataka, the BJP's only stronghold in the south and where Modi invested personally in campaigning, was touted by Congress officials as the beginning of its comeback nationally.

"This is an amazing beginning," said Rajeev Gowda, the head of research at Congress and a former federal lawmaker. "The momentum is picking up for a fight back ... Each state victory can help keep the momentum."

The bread-and-butter issues of unemployment and inflation that Congress highlighted in Karnataka, Gowda said, are critical issues nationally as well, especially as the Indian economy's recovery after the pandemic was uneven.

Milind Deora, a former federal minister from Congress, said there was new momentum after Congress leader Rahul Gandhi's 135-day cross-country march to revive the party, a win last November in Himachal Pradesh state, and now Karnataka.

"We need to adapt these learnings to every election-going state in 2023 and more importantly to parliamentary elections next year," he said.

"Nothing is impossible in politics."

BJP officials countered, however, that the Karnataka result was unlikely to be replicated nationally, especially since Indians tend to differentiate between regional and federal concerns.

A reputable pollster who got the Karnataka results right backs the BJP's view.

Asked by the India Today-Axis poll how they would vote if the Karnataka election had been a national election instead, 10% of the respondents shifted to Modi, enough to overturn the result.

"We have to learn from every loss ... but it must also be recognised that we won three states this year and going ahead there are five elections to come," BJP spokesperson Nalin Kohli said.

"Each of these states have different challenges and we cannot have a common strategy."

(Reporting by YP Rajesh; Additional reporting by Rupam Jain; Editing by Edmund Klamann)