Tayyip Erdogan's ambitions for a swift move to strong presidential rule could suffer if dissidents in Turkey's nationalist opposition succeed in a party leadership challenge that could bolster their party's electoral support. A bid by several hundred members of the Nationalist Movement Party (MHP) to challenge Devlet Bahceli, leader for much of the last two decades, at a special congress set for May 15 was approved by an Ankara court last month. But rallying around its veteran leader, the MHP challenged that decision and an appeals court ruling is pending. Five candidates want to challenge Bahceli, including Meral Aksener, a 59-year-old woman who served as interior minister in the 1990s. "I think this congress will happen on May 15. I think the vast majority of our great congress delegates will be there on that day," Aksener said in a statement that appeared to pay no heed to appeals court deliberations. Uncertainty around Erdogan's role comes at a time of tension in NATO member Turkey as it faces Kurdish insurrection and spillover of violence from Syria. Western allies' concern for stability is tempered by reservations about what they see as his increasingly authoritarian attitude to media and opposition. Some opinion polls suggest MHP support could rise above 20 percent if the leadership is changed, stealing seats from the ruling AK Party that it needs to change the constitution; but it could fall below the 10 percent threshold needed to enter parliament if Bahceli, 68, remained. ELECTION THIS YEAR? AK Party officials have said Erdogan could seek an early parliamentary election this year to capitalize on the MHP crisis if Bahceli remains in office and polls indicate its support falling below the threshold. "If the appeals court decides the extraordinary congress should be held, we as the MHP leadership and delegates will be there out of our respect for the law," a senior MHP official close to Bahceli told Reuters, asking not to be named because of sensitivities within the party about challenging its leader. "The dissidents used threats to gather signatures for the congress decision ... Even if they hold a so-called congress a significant portion of the delegates will not go to the hall." — Reuters