A look at several key players in Pakistan's upcoming national election that is expected in May:
—PRESIDENT ASIF ALI ZARDARI: The president rode to power on a wave of sympathy following the 2007 assassination of his wife, former Prime Minister Benazir Bhutto, but his tenure has been turbulent and he has long been plagued by allegations of corruption. Zardari will not be participating in the upcoming election, but as co-head of the Pakistan People's Party, which led the last government, he will be a key figure. His unpopularity and anger over the performance of the government during its five-year term could damage the party's run in the upcoming election. The economy is stuttering, energy shortages plague the country and Taliban militants continue to stage deadly attacks.
—BILAWAL BHUTTO ZARDARI: The only son of the president and his late wife, he is set to carry the torch for the Bhutto family political dynasty in Pakistan. His grandfather, Zulfikar Ali Bhutto, founded the PPP and served as the country's president and prime minister. He is too young to participate in the upcoming election — the minimum age is 25 — but will likely play a key role as co-head of the PPP with his father. It remains to be seen how well the Oxford-educated youth can rally the party's largely poor, rural constituency in southern Sindh province since he has lived most of his life outside the country and is still working on his command of Urdu, the national language.
—NAWAZ SHARIF: The head of the main opposition party, the Pakistan Muslim League-N, hopes to become prime minister for the third time. His party, which appeals to an industrialist base and is strongest in central Punjab province, is the PPP's main rival to form the next government. Sharif was ousted as prime minister in a bloodless coup in 1999 by Gen. Pervez Musharraf and was sent into exile the following year. He and Bhutto returned to Pakistan in 2007 to lead their parties in the 2008 elections. Bhutto was killed before the elections were held.
—IMRAN KHAN: Khan is a Pakistani cricket legend-turned-politician who could have a significant impact on the upcoming election. He founded Pakistan Tehreek-e-Insaf, or the Movement for Justice Party, more than 15 years ago, but failed to gain much traction until 2011. That year he marked his rise as a major political player with a rally that drew more than 100,000 people in Lahore, the capital of Punjab province. Khan has appealed to a largely young, urban constituency tired with the current crop of politicians and the corruption that plagues the system. Analysts doubt his party can win enough seats to form the next government, but it could steal key votes away from the PML-N and the PPP, especially in Punjab, and that could affect who wins.