Ankara (AFP) - An Ankara court opened a hearing on Monday into alleged vote buying that could upend the leadership of Turkey’s main opposition CHP party, which has been battling a growing array of legal challenges.

On the eve of the case, vast crowds of protesters packed into Ankara’s Tandogan Square in a huge show of defiance over the move, which observers say could have a big impact not only on the party but on Turkish democracy.

Critics say the vote-buying case is a politically motivated attempt to undermine Turkey’s oldest political party, which won a huge victory over President Recep Tayyip Erdogan’s AKP in 2024 local elections and has been rising in the polls.

The CHP denies the charges and has accused the government of trying to defang it as an opposition force.

When the hearing opened at 10:00 am (0700 GMT), the small courtroom at Ankara’s Diskapa courthouse was packed with journalists and lawyers, with some legal professionals not even able to enter, an AFP correspondent said.

Ugur Poyraz, one of the lawyers representing the CHP, asked the judge to move the hearing to a bigger room, saying: “Millions are watching you, your honour. Your decision is very important.”

Outside there was a heavy police deployment, with armed police at the entrance and hundreds more in riot gear waiting in buses parked nearby, the correspondent said.

The case seeks to overturn the result of a CHP congress in November 2023 on grounds of vote rigging.

The congress ousted longtime party chairman Kemal Kilicdaroglu and elected current leader Ozgur Ozel.

If successful, it could unseat Ozel as leader.

“This case is political. The allegations are slander… This is a coup (and) we will resist,” roared Ozel to a sea of flag-waving supporters in Ankara on Sunday.

“We are facing the grave consequences of Turkey’s government abandoning the ‘democracy train’ and choosing to govern through oppression rather than the ballot box.

“Anyone who poses a democratic threat to the government is now the government’s target.”

- Assault on democracy? -

The CHP’s popularity has grown since it led Turkey’s biggest street protests in a decade, triggered in March by the jailing of its presidential candidate, Istanbul mayor Ekrem Imamoglu.

The indictment names Kilicdaroglu as the injured party and seeks jail terms of up to three years for Imamoglu and 10 other CHP mayors and officials for “vote-rigging”.

Ozel and eight other lawmakers are also being investigated on similar charges but their case is being handled by a parliamentary unit because they all have immunity.

On September 2, a court ousted the leadership of the CHP’s Istanbul branch over allegations of vote-buying at its provincial congress, appointing a trustee to take over in a move widely seen as a test run for Monday’s case.

The ruling sparked angry protests and prompted the stock market to tumble 5.5 percent, raising fears that Monday’s outcome could also damage Turkey’s fragile economy.

If the Ankara court annuls the results of the CHP congress, it could herald the return of former leader Kilicdaroglu, who chalked up a string of electoral defeats that left the party in crisis.

In a move to safeguard the leadership, CHP has convened an extraordinary congress on September 21, the idea being that if the court removes Ozel, members could simply vote him back in six days later.

Istanbul’s jailed mayor denounced the case as an assault on democracy.

“This isn’t about the CHP, it’s about the existence or absence of democracy in Turkey,” Imamoglu told reporters on Friday after appearing in court on unrelated charges.