Politics can be a blood-soaked affair in Pakistan, and this leadership struggle is no exception. Dozens have been killed in attacks in the weeks leading up to this Saturday's election.
And yet, this poll is expected to mark a milestone in Pakistan's 66-year history: The first democratic transition of power. The nation has experienced three military coups, been ruled by generals for half its life, and it remains mired in near-constant political turmoil.
But the former government defied expectations by becoming the first elected to serve a full five-year term.
"Despite all the odds, completion of the term is an extraordinary and historic achievement," Prime Minister Raja Pervez Ashraf said in an address to the nation on March 16, marking the end of the term and the start of the election season now coming to an end.
The government may have survived, but the country has lurched from crisis to crisis.
Here are some of the main developments from the last five years of political turmoil.
The nation collectively mourns the death of PPP leader Benazir Bhutto, who is assassinated just months before the elections in February 2008. The Pakistan Peoples Party -- led by Bhutto's widower, Asif Ali Zardari -- comes to power on the back of a populace disillusioned with then-President Perez Musharraf. He leads a coalition with Nawaz Sharif's Muslim League party, however the alliance collapses when Sharif pulls out after failed efforts to secure the release of dozens of judges put under house arrest by President Musharraf during a state of emergency in 2007.
In August of the same year, Musharraf resigns as president, clearing the way for Zardari to take over the post.
On May 2, U.S. President Barack Obama announces the killing of Osama Bin Laden, who was living in hiding at a compound in Abbottabad, Pakistan. The incident underlines the often fractious relationship Washington has with Islamabad, whose leaders had long said Bin Laden was not hiding in Pakistan. Pakistan's parliament adopts a resolution condemning the U.S. raid and Musharraf brands it a "act of war."
In October, Pakistani businessman Mansoor Ijaz claims in an op-ed piece for the UK-based Financial Times that a Pakistani diplomat had him deliver a secret memo to U.S. Admiral Mike Mullen, who was then the chairman of the Joint Chiefs of Staff. The memo, allegedly from Zardari, reportedly asked the U.S. to back him in the event of a military coup related to the U.S. killing of Osama bin Laden. The government said it had nothing to do with the memo.
In December, Pakistan's Supreme Court appoints a panel to investigate the memo.
In February, Yousuf Raza Gilani becomes the first Pakistani prime minister to be charged while in office. He's accused of contempt for refusing to re-open old corruption cases against Zardari.
Two months later, Gilani is convicted and receives a symbolic sentence of custody for the duration of the hearing. He refuses to resign and vows to appeal.
In June, Pakistan's Supreme Court rules that Gilani is ineligible to hold office. The court declares the prime minister disqualified retroactive to April 26. Raja Pervez Ashraf is appointed prime minister after majority vote in parliament.
Later in the year, the Pakistani Taliban claims responsibility for a series of attacks on Shiite Muslims. In the months ahead, militants stage further attacks against Shiites in an attempt to disrupt the election.
In January, the Supreme Court orders the arrest of Ashraf over corruption allegations which one of his advisers calls a "soft coup" against democracy. Ashraf denies the claims.
In March, a caretaker government is appointed to oversee parliamentary elections.
March 24 -- Musharraf lands in Karachi after more than four years in exile. He faces criminal charges, and the Taliban vow to unleash a "death squad" to assassinate him.
He returns to face a lengthy list of charges, including accusations he illegally deposed and detained 62 senior judges during a period of emergency rule in 2007, and not doing enough to protect the life of Bhutto, the country's first woman to be elected prime minister of Pakistan. He denies any wrongdoing.
April 11 -- A candidate in May's 2013 national elections in Pakistan is shot and killed by two gunmen on a motorbike. Candidate Fakhar Ul Islam was targeted on his way home from his office, police said. Islam was a member of Muttahida Quami Movement or MQM, Pakistan's most liberal and secular political party.
April 12 -- Musharraf acknowledges his government secretly signed off on U.S. drone strikes, the first time a top past or present Pakistani official has admitted publicly to such a deal. His admission to CNN runs counter to their repeated denunciations of a program they long claimed the United States was operating without their approval.