AMNA NAWAZ: India has reelected Narendra Modi as prime minister, making him only the second leader in the nation's history to secure a third term.

But Indian analysts call the results a shock, because Modi's party lost at least 20 percent of its parliamentary seats, forcing him to rely on a coalition.

And, as Nick Schifrin reports, that could affect how Modi will govern after 10 years in power.

NICK SCHIFRIN: At his party headquarters in New Delhi tonight, Narendra Modi entered with triumph despite an election that left him humbled.

NARENDRA MODI, Indian Prime Minister (through translator): For this blessing, I am indebted to all citizens.

Today is an auspicious day.

NICK SCHIFRIN: Modi fought the election in his own name, promising a rising, stronger India.

But many of the 640 million Indians who voted over seven weeks voted their pocketbooks.

SUSHANT SINGH, Yale University: This was the economic crisis which a large number of Indians, but particularly from rural India and lower socioeconomic strata, were facing.

And they are the ones who have really voted Mr. Modi out -- or have voted against Mr. Modi.

NICK SCHIFRIN: Sushant Singh is an Indian journalist and lecturer at Yale University.

He says rural Indians worried about the economy were also worried Modi would amend the Constitution to revoke special rights for underprivileged communities, as opposition leader Rahul Gandhi said today.

RAHUL GANDHI, Indian National Congress: I'm extremely proud of the people of India.

I'm extremely proud of the people who have resisted this onslaught on the Constitution.

SUSHANT SINGH: This really put the fear in the ranks of these vast masses of so-called unschooled poor Indians, who thought that something which gives them political rights, something which gives them some kind of path for economic progress, that has been -- that is likely to be taken away.

And the two factors combined together to deliver what many believe is a stunning result.

NICK SCHIFRIN: Among those who voted against Modi, his own stronghold, the northern state of Uttar Pradesh.

Modi's party lost more than half its seats, including the district where, in January, Modi inaugurated a grand temple on the site where a 16th century mosque was demolished.

SUSHANT SINGH: It was the battleground state around which Mr. Modi's party gained majority in last few times.

That was a stunning result by itself.

And, actually, it encapsulated what had happened in the Indian election.

NICK SCHIFRIN: A decade of Modi's rule has been in part defined by violence on religious minorities and a crackdown on civil society, the opposition and press freedom.

A coalition government could force Modi to rein it in, says Singh.

SUSHANT SINGH: Because Mr. Modi is now a much weaker leader, much weaker prime minister, dependent on his coalition partners, we will definitely see some of these institutions rediscover their voice, rediscover their conscience and start saying things which we have not heard from them for the last decade.

JOE BIDEN, President of the United States: Today, the partnership between our countries is stronger than it has ever been.

NICK SCHIFRIN: But Modi has also helped make India indispensable to U.S. plans in Asia, as the Indian military defends Indian territory from Chinese soldiers and the U.S. hopes for India's help to confront China.

SUSHANT SINGH: Irrespective of whoever is leading India, any U.S. administration, whether Republican or Democrat, will continue to work with India because of the China factor.

NICK SCHIFRIN: And so U.S.-Modi cooperation will continue, but the man who described himself as heaven-sent now faces the ground reality of the voters.

For the "PBS NewsHour," I'm Nick Schifrin.