Mullah on the march: Pakistan cleric takes on Imran Khan

party. Still smarting from that loss, Rehman has chosen this moment carefully.

Khan's government has been under pressure for months as anger simmers over the dire state of the economy. Unemployment, double-digit inflation, and rising utility costs have hit ordinary Pakistanis hard -- issues other opposition parties have also railed against -- and Rehman has been eager to exploit the unhappiness during the march.

As the protest moved toward the capital this week, traders across the country launched a two-day strike, piling further pressure on Khan. The cleric insists that Khan needs to be removed from office, and a new "free and fair" election held.

But he remains vague about how he aims to achieve their goals. That lack of substance has led some observers to suggest Rehman's protest is more a salve for his ego after the humiliating election drubbing.

"He's been left out of a game and he thinks he's been cheated out of his rightful place," said columnist Arifa Noor. "The (economy) is more of a stick to beat the government with." Rehman has rotated in and out of successive governments for decades, forging alliances with both Islamist and secular parties while enjoying occasional support from the military establishment.

He was once a hardline Islamist and anti-American firebrand, calling for the implementation of Shariah law publically backing the Afghan Taliban, but more recently has tried to rebrand as a moderate. That has not stopped him from dismissing the attack on Nobel prize laureate Malala Yousafzai in 2012 as a fabricated conspiracy, and protesting the exoneration of Asia Bibi -- a Christian woman at the centre of Pakistan's most high-profile blasphemy case.

Whether the march ends in violence or not, it has undeniably thrust Rehman back into the spotlight after suggestions he was increasingly becoming irrelevant. "When was the last time the maulana dominated the news agenda this much?" asked Noor.