WARSAW (Reuters) -- Poland's Peasants' Party (PSL) said on Tuesday only substantial concessions would enable it to form a new governing coalition with the ruling conservatives, whose previous alliance collapsed last week.

With 25 deputies in the 460-member parliament, the PSL can play kingmakers after the conservative Law and Justice party (PiS) ditched leftist partners Self-Defense in a row over the 2007 budget and a decision to send troops to Afghanistan.

If the rural-based party does not agree to a coalition by parliament's next sitting beginning Oct. 10, the conservatives have said they will seek snap polls, three years before their term of office runs out.

"(For us to agree to a coalition) there will have to be substantial changes to policy, both socially and economically," the head of the supervisory board of the Peasant's Party, Jaroslaw Kalinowski, told private radio RMF on Tuesday. "I have talks with PiS tomorrow. Our party leadership will meet today ... Looking at what PiS has done over the past few days, I have fears. The chances (of a deal) are minimal."

Prime Minister Jaroslaw Kaczynski said after his coalition collapsed last Thursday that he would push for early elections, possibly on Nov. 26, if he fails to put together a new majority.

Coinciding with anti-government protests in Hungary, the crisis worried investors concerned that reforms would stall in ex-communist states that joined the European Union in 2004.