The Congress on Thursday won the mayor's post in Siliguri Municipal Corporation in north Bengal with the support of Left Front councillors, defeating ally Trinamool Congress, which had refused to concede it.
Sources in the corporation said Congress candidate Gangotri Dutta received 32 votes against TC aspirant Goutam Deb's 15 in the 47-member board.
Reacting to the result, TC candidate Deb said the election had "exposed the character" of the Congress, which had always had "good relations with Marxists".
"We have decided to sit in the opposition and let the Left Front and the Congress run the board," he said.
In the September 13 elections in the corporation, the TC and Congress combine wrested the majority from the Left Front after 27 years by winning 30 seats while the latter won 17 seats.
Since the United Progressive Alliance allies failed to reach a consensus on the post of mayor, both the parties fielded their own candidates for the post.
Amid the impasse, the Congress, which won 15 seats, on Wednesday appealed to all the elected members to support their candidate Dutta.
Dutta received the support of all 17 Left Front councilors 15 of the Communist Party of India-Marxist and one each of the Revolutionary Socialist Party and the Forward Bloc.
Kolkata Congress Committee Working President Pradip Bhattacharya said his party's win would not affect the alliance with the TC.
"I don't think that this will harm the alliance between the Congress and the TC since this is purely a local issue," Bhattacharya said.
On TC's criticism for taking the support of Left Front councillors, he said, "This is not a state political issue that can endanger the alliance."
"The Congress will definitely maintain the alliance with the TC in the 2011 assembly elections to rout the CPI-M-led Left Front and form a non-Left government in the state," he said.