SURAT, India — The immense popularity of Narendra Modi, India’s most dynamic prime minister in decades, has always rested on two legs: Hindu nationalism and his tantalizing promises to build on the country’s go-go economy.

That second leg is now looking a little shaky.

In the last two years, India’s consumer confidence has plummeted, construction has slowed, the fixed investment rate has fallen, many factories have shut down, and unemployment has gone up.

Fingers are pointing at Modi. Just about all economists agree that two of the prime minister’s biggest policy gambles — abruptly voiding most of the nation’s currency and then, less than a year later, imposing a sweeping new sales tax — have slowed India’s meteoric growth.

“Things have been worsening, worsening, worsening,’’ said Himanshu, an economics professor at Jawaharlal Nehru University in New Delhi, who uses only one name.

Still, the economy here is far from failing. The stock market continues to soar; major rail, road, and port projects are unfolding across the country; and foreign investors poured $25.4 billion into India from April to September, up 17 percent from the period in 2016.

The government on Friday predicted that the country’s gross domestic product would grow by 6.5 percent in the 2017-18 financial year. While that is the lowest number the country has seen in four years, India’s economy is one that most countries would love to have.

But it does not feel that way to the huge number of Indians negatively affected by Modi’s policies, and the grumbles are growing. So are social tensions, especially those that divide Hindus from Muslims, and upper caste from lower caste.

The fear is that Modi is already beginning to lean more heavily on that first leg of his, Hindu nationalism, now that his economic strategy is losing some of its sheen.

With 1.3 billion people, India is the world’s most populous democracy. In 10 years, economic forecasters predict that India’s economy will climb to third-largest in the world, behind only the United States and China. What happens here matters, and domestically, confidence is strained.

Even in Gujarat, the state considered the strongest of Modi’s strongholds, where people have been cheering his rise for the past 20 years and line up in dusty fields by the thousands just to catch a glimpse of his saffron scarf and groomed white beard, many feel betrayed.

The output from the textile industry, a huge employer here and once a healthy exporter, has been cut nearly in half, prompting layoffs and despair.

In many of the industrial areas, the happiest merchants are the merchants of scrap, who make their rounds in lurching trucks, scooping up looms, steel spools, and other underused machinery for pennies on the dollar.

In December, in an election that the entire country was watching because it was seen as a referendum on Modi’s governance, Gujarati voters elected a new state Assembly. Modi’s party maintained its majority but lost 16 seats.

The message was clear: Modi’s party was still No. 1, but the man himself was no longer bulletproof.

“Modi hurt our business, and we want to show him that we can hurt him, too,’’ said Manish Patel, whose once clackety cloth factory is now completely empty, another Gujarati business that has gone under.

Patel complained that under Modi, “It was like we were in first class and now we’ve been put in 10th class.’’

So for the first time in his life, Patel voted for the Indian National Congress, the leading opposition party, not for the Bharatiya Janata Party of Modi.

Here in Surat, a Gujarati metropolis with hundreds of years of storied mercantile history, Modi’s currency policy hit like a sledgehammer. It was November 2016, and when Modi abruptly announced that large denomination rupee notes were invalid and being replaced with new currency, panic erupted.

Manish Patel and his older brother, Dilip, who run the family’s cloth business, found themselves scurrying into line at the bank and waiting hours each day, trying to get money.

It was never enough, and when the brothers could not pay their loom operators, many walked off. Hundreds of factories had the same problem. The Surat textile traders association said production in this area dropped to 25 million meters a day now from 40 million meters two years ago.