THE WORLD’S biggest democratic election began Monday. The result, for better or worse, is easy to foresee. Polls show India’s Bharatiya Janata Party and its leader, Narendra Modi , beating the ruling Congress Party by as much as 3 to 1 among the more than 800 million people eligible to cast ballots over the next five weeks. The charismatic and hard-charging Mr. Modi promises big change for India, which for the past decade has drifted under the ineffectual Congress government of Manmohan Singh. India and the outside world can only hope that the country’s new administration will reflect Mr. Modi’s considerable strong qualities more than his equally outstanding failings.

The promise of Mr. Modi, and the reason for his wide lead in the polls, is clear: a tough, practical and corruption-free record of economic management. As chief minister of Gujarat state, Mr. Modi has overseen growth averaging 10 percent a year over the past decade, significantly higher than for the country as a whole. His success rests on smart investments in infrastructure, business-friendly policies and openness to foreign capital.

Just the prospect that Mr. Modi would take charge of the central government has sent the Indian stock market and rupee soaring and prompted a wave of foreign investment. The country unquestionably needs the medicine he seems to offer. Growth has recently slowed to 5 percent , too little to soak up the growth in the labor force, and much of the malaise can be traced to the troubles Mr. Modi has shown he can tackle, at least on a much smaller scale: energy bottlenecks, excessive regulation and choking corruption.

Mr. Modi, however, may be as repellent to India’s Muslims and secular liberals as he is attractive to the business community. A lifelong member of a quasi-martial Hindu nationalist movement, he is reviled by human rights groups for his behavior during and after anti-Muslim riots in Gujarat in 2002, in which more than 1,000 people died. Critics say Mr. Modi at best did nothing to stop the violence, then exploited anti-Muslim feeling in an election campaign. In 2005 this record prompted the State Department to deny him a U.S. visa.

Mr. Modi has abandoned anti-Muslim rhetoric — “My real thought is toilets first, temples later,” he said in one campaign speech — but he has not apologized for or even explained his actions in the 2002 riots. He has a record of hostility toward journalists and their questions and rarely grants interviews. Worse, he has cultivated an autocratic style in government and, as head of the BJP, systematically purging critics and potential rivals.

At worst, a Modi government could erode India’s robust democracy and exacerbate religious tensions that in recent years have abated. But India’s political culture is resilient and resistent to such extremism. Though critics had similar worries when the BJP’s first government took office in 1998, they were mostly not borne out. The Obama administration, which in February broke its freeze-out of Mr. Modi, is right to bet that he will follow through on his promise to build the economy rather than picking sectarian fights.