President Obama starts his three-day visit to India hoping to strengthen America’s political ties and expand American trade relations with the world’s largest democracy. Indians, in turn, expect that America will open its doors to even more imports from the world’s second fastest growing economy — after China — and will further ease the path for India, also a nuclear power like China, to acquire nuclear technology for civilian uses.

Both parties would be wise to prepare to be disappointed when Mr. Obama leaves India for the next stops on his Asian journey — Indonesia, where he went to school as a child, Japan, and South Korea. For Mr. Obama and the Democrats have been curiously naïve about the Indian polity, and the Indians have miscalculated the ability of this, or any, president to shape American foreign policy, notwithstanding the constitutional power the White House has to consider world affairs as its near-exclusive domain.

None of this is not to say that the 200-plus business executives who are accompanying the president to India will depart away empty-handed. America, after all, is India’s biggest trading partner, after the United Arab Emirates. Although India’s ranking is only 28 among America’s trading partners — number one being Canada — Indian exports, such as textiles, chemicals, and jewelry have the potential to improve the country’s trade standing in America.

Mr. Obama will be more concerned about American exports to a market of 1.2 billion people, one whose middle class of 450 million constitutes the biggest and hungriest in the world for consumer goods. India’s long-closed economy has been fitfully opening up to foreign products, and local manufacturers are no longer looking askance at foreign companies that were considered implacable enemies until 1991, when an economic minister, Manmohan Singh, unveiled economic reforms to put India on the road to greater free enterprise and Mr. Singh himself on track to be the prime minister who is greeting Mr. Obama.

Those reforms have not gathered as much velocity as one would hope, primarily because the Indian political system has become increasingly fractious. More parties than ever before occupy the 545-member lower house of the parliament, the Lok Sabha, and the 250-member upper house, known as the Rajya Sabha. No single party has a clear majority in either house, particularly in the Lok Sabha which enacts critical legislation. The dominant player, the Indian National Congress led by the Italian-born Sonia Gandhi, leads a kaleidoscopic coalition of parties ranging from the center-left to centrist to the center-right. The Congress is the first among equals of the grouping known as the United Progressive Alliance.

Precisely because it’s a grouping, Mr. Singh — who serves at the pleasure of Mrs. Gandhi, widow of the late Prime Minister Rajiv Gandhi, who was assassinated by a Sri Lankan terrorist in May 1991 — can take little part in governance. He first has to seek Mrs. Gandhi’s approval on all policy undertakings, but particularly economic ones; Mrs. Gandhi has yet to fully disengage herself from her European neo-socialistic sensibility. Then Mr. Singh has to negotiate with leftist elements who continue to espouse anti-capitalist sentiments.

Then there’s the corruption that’s become cancerous in India. There is a joke in Mumbai and Delhi, cities that Mr. Obama is scheduled to visit, that Indian factotums, acting unilaterally or on behalf of certain cabinet ministers known for their — how to put it — fondness for the good life, have negotiated a price for every member of the president’s entourage. All by way of saying that doing business with India is simply a matter of doing business. It’s perhaps more to the point to assert that doing business means practicing politics India-style, politics where the truly corrupt rarely get prosecuted and where those prosecuted seldom serve time.

Because of the Foreign Corrupt Practices Act of 1977, American companies are forbidden from greasing palms overseas. Nevertheless, Mr. Obama will have to adjust his arithmetic to factor in the cost of doing more business with India. The American business community has long understood this, but the president, with his didactic dedication to impractical politics, may not be willing to play the Indian game. He may also be unwilling to butt heads against the newly elected Congress, which may not favor a civilian nuclear deal that President Bush and Mr. Singh shook hands on in 2005, though the pact was approved by the Democratic-led Congress in 2008, ending years-long nuclear-trade sanctions established after India conducted, in 1974, an atomic test using material produced by a Canadian company.

Indians, meanwhile, are going to have to learn how to deal the opposition to ob-outsourcing that several major Democrats have been putting up noisily. One way would be to significantly increase the Indian private-sector’s current investment in America of $11 billion, and create jobs in America itself at a time when Mr. Obama’s policies have yet to meaningfully alleviate unemployment.

Lest all this sound difficult, it is well to remember that Mr. Obama, like his predecessor, has a strategic interest in reaching out to India, which has emerged beside America as both a target of Islamist extremism and an ally in the struggle against it. This was thrown into sharp relief with the attacks on Mumbai, and mark a major realignment in the region from the days of the Cold War, when India was part of the so-called non-aligned bloc. By this measure the contretemps over the cost of Mr. Obama’s visit can be seen as frivolous. And the importance of the strategic partnership will not be lost on Communist China.

Mr. Gupte, a contributing editor of The New York Sun, is at work on a book on India and the making of the modern Gulf that is due out in the spring.