ISTANBUL — Five months ago, Selahattin Demirtas, a popular Kurdish politician jailed for his fiery speeches targeting Turkish President Recep Tayyip Erdogan, staged an unlikely challenge from his prison cell to unseat Turkey’s ruler, finishing a surprise third in the historic vote.

Now, Demirtas spends his days writing fiction or preparing his defense in the dozens of prosecutions he faces as he marks his second year in prison this month. His Twitter account, from which he staged virtual “campaign rallies” and poked fun at this confinement, is silent for weeks at a time. In his absence, his Peoples’ Democratic Party (HDP), the parliament’s third-biggest grouping, has chosen new leaders but struggled to make its voice heard amid a media boycott and after thousands of its activists were arrested.

A European Parliament report this week counts Demirtas’ jailing among the human rights violations that should halt European Union membership negotiations with Turkey. Chances for the country’s long-running bid to join the EU have become even more remote in the wake of a failed military coup in 2016 and the ensuing clampdown.

Demirtas, his co-chairwoman Figen Yuksekdag and seven other former and current lawmakers have been in prison since Nov. 4, 2016, charged with terrorism-related offensives stemming from their political speeches. Erdogan accuses them of aiding the armed Kurdistan Workers Party (PKK) after a peace process the HDP helped the government broker collapsed in 2015, unleashing the deadliest violence in two decades.