In cities across India, the beaming face of Prime Minister Narendra Modi adorns giant posters promoting the country’s G20 presidency. A hundred national monuments, including the Red Fort in Delhi, were illuminated with the G20 logo to encourage people to post selfies. Government reading lessons inform students that India is a fitting G20 host because it is “the Fountain Head of Democracy.”

To behold the advertising and public relations blitz that the Indian government has mounted as it prepares to hold the Group of 20 summit this weekend, one might think India had been personally anointed by its peers, rather than merely being next up in the rotation.

But India, and its governing party, were primed to capitalize on the moment.

The G20 has arrived just as India is asserting itself as a rising geopolitical and economic force, courted by an array of global powers and offering itself up as a leader and model for developing nations. Mr. Modi has seized on the G20 presidency as confirmation and celebration of India’s ascent — a rise to which he has fused his own image — as he seeks a third term in an election early next year.

Mr. Modi has been a master political marketer ever since his time as a state leader, “and now he is also making good use of the G20,” said Neerja Chowdhury, a political analyst and editor. “That India has arrived on the world stage will go strongly in his favor with the electorate.”

To the prime minister’s opponents, the promotional barrage has been an unseemly political hijacking of an international gathering intended to foster economic cooperation. India’s G20 logo features a lotus, the symbol of Mr. Modi’s Bharatiya Janata Party, or B.J.P. At a launch event for the logo, he proclaimed that even at a time of global crisis, “the lotus still blooms.”

Television shows and newspapers in the B.J.P.-dominated media landscape have raved nonstop about India’s moment in the spotlight. The government is reported to have spent more than $100 million on over 200 G20-related events across dozens of Indian cities, a level of fanfare that has redefined — perhaps uneasily for future hosts — what it means to hold the G20 presidency.

The events have taken on the feel of a barnstorming carnival and, in effect, have allowed Mr. Modi to start campaigning long before the start of the political season. If Mr. Modi’s party reaps political dividends from the G20, it is well deserved, his lieutenants say.

“Why shouldn’t G20 be used for domestic politics? If G20 has come to the country during Modi-ji’s time and it is completed with success, then Modi-ji must get credit,” Amit Shah, the home minister, told an Indian news outlet in February, using an honorific with Mr. Modi’s name.

B.J.P. politicians have said that the G20 is a chance to show the “best face” of this country of 1.4 billion people.

Delegates at the events leading up to the summit have been treated to an array of Indian delights. Guests who visited Kashmir received walnuts, saffron and papier-mâché gifts. They were also taken to famed Mughal gardens and for boat rides on a pristine lake in an effort to project an air of normalcy in the restive Himalayan territory, where democracy has been suspended for the whole of Mr. Modi’s second term.

In Gujarat, his home state, delegates were kept entertained between meetings with fashion shows and a night featuring local dance. Delegates participated in a yoga session in the south Indian temple town of Hampi and went on quaint heritage walks to palaces and forts in the central Indian city of Indore.

At the Taj Mahal, a vertical garden was set up so V.I.P.s could take selfies. One of its supposed benefits was to keep away the stench from nearby drains. But the garden collapsed, a victim of a “monkey attack,” according to a government official.

Even humble millet — India is the world’s largest producer — has found itself in the G20 spotlight. A millet-heavy menu, including in dosas and pancakes, will greet delegates this weekend at hotels and restaurants across New Delhi.

Schools are getting in the G20 spirit, too. Teachers have been instructed to organize quizzes and essay- and slogan-writing competitions. Government reading materials — titled “Let Us Learn About Group of Twenty” — encourage students to “write a letter to the Prime Minister of India suggesting him an important idea, point or action” in the G20 agenda. The materials also point to democracy’s deep roots in India, even as the country has taken an authoritarian turn under Mr. Modi.

As many other places have done before hosting a major international event, India has been tidying up and taking steps to ensure visitors’ comfort.

An action plan to keep away deadly dengue-carrying mosquitoes includes “drone-based vector surveillance and concurrent anti-larval spray in the drains.” Cutouts of large monkeys have been installed to keep away the packs of smaller monkeys that sometimes harass people. Videos emerged of municipal workers violently dragging away stray dogs to clear the areas.

A report compiled by activists accused the government of using the G20 as a weapon to “snatch away the basic livelihood and rights” of common people. A spokesman for the B.J.P., Tom Vadakkan, said that the evictions had nothing to do with the G20, and that the government was helping the displaced get adequate housing.

Residents of a recently bulldozed New Delhi slum disagreed.

Squatting on the debris of their belongings, some said they hoped they could return to their original homes someday. Karan, a day laborer who goes by one name, dug out a photo of himself next to a cutout of Mr. Modi, with a multistory housing block in the background.

“We were herded in a bus by some B.J.P. workers earlier this year, just before the local municipality elections, and told we will get these homes after the elections,” he said, teary-eyed. “We were then asked to pose with Mr. Modi’s cutout. Now our homes have also been bulldozed. Where are these homes promised to us, then?”