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 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.
"This is an amazing beginning," said Rajeev Gowda, the head of research at Congress and a former federal lawmaker.
"We need to adapt these learnings to every election-going state in 2023 and more importantly to parliamentary elections next year," he said.
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.