The threatened launch of two new political parties in Zimbabwe is set to deepen the challenges facing President Robert Mugabe and his ruling ZANU-PF party, political analysts say.The Zimbabwe Congress of Trade Unions (ZCTU) has announced it would "facilitate" the formation of a labour party to take on ZANU-PF in legislative elections next year, and in a further flexing of political muscle, promises a tough round of collective wage bargaining later this year.