But the last-minute appeal is likely to have little effect across Uttar Pradesh, where as many as 50 million are expected to vote for 403 seats.

The state has seen campaigning from a cast of colourful characters that include a feisty woman from India's untouchable classes and a former wrestler.

Sonia reminded a crowd of some 5,000 Congress stalwarts of the party's history in the independence struggle and asked them not to cede to the caste-based claims of her opponents.

"I want to remind you that the Congress was every Indian's party then and is still every Indian's party today," said the Italian-born Sonia, emphasising the word "every," as she spoke in the blazing heat.

But Congress now has very little support in the northern state, where it has been wiped out in the last 15 years, except in pockets like this rundown former mill town.

Two of the paltry 25 seats that the party won in state polls five years ago were in this city.

Meanwhile, parties that appeal to untouchables -- or Dalits as they are now known -- at the bottom of the caste system and "other backward class" Hindus have forged ahead across the state.

"You have to decide whether you want parties that divide the people among themselves to form the next government or a government that takes everyone forward together," she said in fluent but accented Hindi.

The ten-minute speech met with polite clapping from the motley crowd rounded up by party workers from some of the city's poorer sections and ferried to the dusty Moti Jheel park where red and white plastic chairs had been laid out.