(CNN) -- The strongest contender to become the next Pakistani prime minister is hardly a newcomer to the country's political stage. Nawaz Sharif, 63, has had a long and rocky career that includes two stints as prime minister during the 1990s, ordering Pakistan's first nuclear tests, a showdown with the nation's powerful military, time in jail and years of exile. After spending the past several years in opposition to the governing Pakistani People's Party (PPP) -- which has struggled to tackle the country's crippling problems of militant violence, chronic power shortages and a flagging economy -- Sharif now has a shot at another stint in office.
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Nawaz Sharif, a frontrunner in Pakistani elections, has been prime minister twice
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He was overthrown in a 1999 coup and went into exile in Saudi Arabia
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He is now campaigning with a promise to revive Pakistan's economy
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Observers have raised questions about his stance on extremism and terrorism
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