The Congress on Tuesday said it had "no problem" in joining hands with the Left parties and all options were open for alliances after the April-May Lok Sabha elections.
"All options are open. We want to ensure that the Bharatiya Janata Party (BJP) does not come to power," Congress general secretary Digvijay Singh told reporters.
Asked about a reported meeting of Left leaders with Amar Singh of the Samajwadi Party, with which the Congress is discussing an alliance, Digvijay Singh said: "We have no problems with the Left."
Amar Singh is reported to have met Communist Party of India (CPI) leader AB Bardhan.
The Left parties, which pulled back support to the Congress-led United Progressive Alliance government over the India-US nuclear deal in July 2008, have been speaking of forming a non-Congress, non-BJP 'third' alternative.
In reply to another question, the Congress leader said the party would not campaign for former BJP leader Kalyan Singh, who is negotiating a tie-up with the Samajwadi Party in Uttar Pradesh.
"We believe he is responsible for the demolition of the (Babri) masjid and we will not share a platform with him," the Congress leader said.
The Babri mosque was demolished in December 1992 in Ayodhya when Kalyan Singh was Uttar Pradesh chief minister.