Pauline Marois is warning a rival sovereigntist party to stop attacking the Parti Quebecois — or risk handing the election to the Liberals.
Marois says Francoise David, the spokeswoman for the small, social-democratic Quebec solidaire, should focus her attention more on Liberal leader Philippe Couillard.
She says the PQ and Quebec solidaire are both progressive and pro-Quebec independence and must work together to avoid a Liberal government.
Although Quebec solidaire only holds two seats in the Quebec legislature, polls suggest the party's popularity has climbed in recent weeks.
Quebec solidaire could steal away votes from the party's left-leaning voters in the April 7 election.
David has argued the PQ has shifted its policies to the right since taking government in 2012.