People shout slogans and let off flares outside the Justice and Development Party headquarters in Istanbul on June 24, after counting of votes in Turkey's presidential and parliamentary elections commenced. (AFP photo)

ANKARA, June 30 (Xinhua) -- Entangled in a wave of disillusionment after Sunday's crushing defeat in the elections against President Recep Tayyip Erdogan, the leadership of Turkey's largest opposition party is facing mounting calls to resign to pave the way for "new blood."

The pro-secular Republican People's Party (CHP) has entered a period of showdown between incumbent and long-time chief Kemal Kilicdaroglu and the party's presidential contender Muharrem Ince.

Erdogan, who has been ruling Turkey since 2003, won the crucial general elections with 52.6 percent of votes, acquiring unprecedented executive powers approved by referendum last year.

Ince scored a respectable 30.6 percent of ballots, but still failed to challenge the Turkish strongman in the second-round run-off as most surveys had predicted.

Erdogan's ruling conservative Justice and Development Party also exceeded expectations and garnered a majority in parliament with the support of his nationalist ally, the Nationalist Movement Party.

Kilicdaroglu, 69, told a news conference on Tuesday that the charismatic and younger Ince, who is 54 years old, scored "below expectations," a remark regarded as ungracious by many CHP supporters on social media.

Banners of Turkish President Recep Tayyip Erdogan and a banner of Muharrem Ince, presidential candidate of the main opposition Republican People's Party hang in a street in Istanbul, Turkey, on June 16. (Reuters photo)

Meanwhile, he praised his party's performance, which is nevertheless almost 3 percent down from its 25 percent of votes in the last parliamentary elections in November 2015.

Kilicdaroglu, however, insisted that his party did quite well in the elections, which he said were held under emergency rule and in unfair conditions.

The party chief also dismissed suggestions that he should quit.

Ince, a former physics teacher and long-time lawmaker engaged in an energetic campaign across Turkey, won the heart of millions of CHP supporters, as well as appreciation from other political camps including the Kurdish population in the heavily polarized country.

For now, the calls for Kilicdaroglu to resign are mounting, with some lawmakers and grass-roots supporters pushing for a party congress to elect a new leader before the next electoral test, the municipal elections scheduled for March 2019.

Ince tweeted to calm his supporters, saying he would visit all 81 provinces of Turkey to "thank" the people, a move which has been interpreted by commentators as an initiative to start a challenge against the CHP's leadership.

Kilicdaroglu, for his part, slammed rumors over internal divisions in the party.

"Muharrem Ince is an asset for us. We are embracing him to the end," he said.

Ince's supporters have staged a sit-in in front of the party headquarters in the capital Ankara, demanding an extraordinary congress be convened as soon as possible in order to elect him chief of CHP and criticizing the "ineffective opposition style" of incumbent Kilicdaroglu.

Erdal Aksunger, a party member and former lawmaker, said Kilicdaroglu "has achieved its mission in CHP," and should pave the way for Ince's leadership.

Ince has challenged Kilicaroglu twice in vain for the party leadership. A third challenge is now on the table despite not for the near future, Cumhuriyet daily quoted CHP members close to Ince as saying.

In the meantime, there are also inside calls for both camps to avoid additional internal tensions.

Bedri Baykam, a veteran member of the party, said in his column in the internet newspaper Odatv that it is important "not to lose the wave of enthusiasm generated by Ince's campaign," saying losing the vibe "would bring turmoil in CHP before the local elections."