As he battles to cling to power after nearly two decades as leader of Turkey's nationalist opposition, Devlet Bahceli is arguably more important to the future of Turkish politics than ever before. The dour 68-year old, who took over the leadership of the Nationalist Movement Party (MHP) in 1997, has done little to move it from the political margins ever since, its popularity declining over the years despite growing nationalist sentiment. But as he fights an increasingly bitter leadership challenge in the twilight of his career, Bahceli has been thrust center stage in the main political saga of the day: President Tayyip Erdogan's effort to accumulate greater powers. Should he stay, support for the MHP could drop to the point that it is forced from parliament, all but guaranteeing Erdogan the backing he needs for a referendum on changing the constitution and forging a stronger presidency. Should he be ousted, his main rival Meral Aksener could take over, a 59-year old woman seen by pollsters as having the mettle needed to revitalize the MHP and increase its support. That could make Erdogan's ambitions harder to push through parliament. "Some time ago a Bahceli victory was seen as definite, but now every possibility is there," said one source close to the ruling AK Party, which was founded by Erdogan and is watching the leadership battle in the MHP with increasing trepidation. Bahceli appears on the back foot. His supporters have tried to block a special party congress called for June 19 by several hundred MHP members at which he could be ousted, but Turkey's court of appeals has ruled it can go ahead. Hakan Bayrakci, head of pollster SONAR, said Aksener, who served as interior minister in 1996-97, would have the support of around 750 of the 1,241 delegates, enough to force him out. But Bahceli's allies are fighting a rearguard action, launching an investigation by the MHP's Central Disciplinary Board — which has the power to ban members from the party — into Aksener and three other challengers. "Our dissident colleagues deserve a punishment for their activities against the party. The board may prevent their candidacy (in a leadership bid)," said one senior MHP official loyal to the veteran leader. Bahceli himself has said the party can go ahead with a congress in July at which he will stand again for the leadership. By then, the disciplinary board may have ruled, but a second Bahceli ally said he would still be taking a risk. "He risks losing his seat by taking the decision to go to the congress," the ally said, speaking on condition of anonymity for fear of undermining Bahceli's position. ‘Inevitable despotism' Pollsters estimate that should Bahceli hang on, support for the MHP could drop to below the 10 percent threshold needed for representation in parliament, down from a peak of 18 percent in 1999 and from 12 percent at the last elections in November. That could prompt Erdogan to call a parliamentary election and strengthen the majority of the ruling AK Party by enough to guarantee support for a referendum on constitutional change. Of all of Turkey's opposition parties, the MHP is the most likely to have some sympathy for Erdogan's ambitions. The AKP also has a deeply nationalist strain, and the two parties have of late been on the same page when it comes to crushing by force a Kurdish militant insurgency in Turkey's southeast.