Meanwhile, State Department spokesperson Morgan Ortagus said under PM Modi, who has been voted back to power with a "stronger mandate", the Trump administration expects India-US ties to reach new heights in the coming years.

The US looks forward to work with the newly-elected Indian government to continue to accelerate the strategic partnership, which includes cooperation on a range of critical issues such as counter-terrorism and ensuring a free and prosperous Indo-Pacific region, she told reporters during an off-camera gaggle here.

"The US-India partnership has never been stronger and never been better, and we certainly expect it to reach new heights in the coming years," Ortagus said.

The spokesperson also praised India's democratic system, saying the country's elections are the world's largest exercise in democracy, "a marvel of logistics and planning with 900 million people -- an eighth of the world's population -- eligible to vote".

"We applaud the high turnout, estimated at around 66 per cent or roughly 600 million people, and the government of India for their excellent execution of this incredible event," Ortagus said.

Congressman Eliot L Engel, Chairman of the House Committee on Foreign Affairs, also wished Indians, who over the course of the past five weeks, voted to elect a new government.

"Voting is one of the most important rights - and responsibilities - of those living in a democracy, and I congratulate the 600 million Indians who exercised this right," he said.

"The Indian people have spoken, and the United States Congress looks forward to continue working with India, and the Narendra Modi-led National Democratic Alliance government to advance our shared goals on a host of issues, including human rights, defence, trade and economic growth, and climate change," Engel said.

The 2019 general election in India was held in seven phases from April 11 to May 19.

Congratulating Modi and his party for their "landslide victory", Congressman Jim Banks tweeted, "The relationship between India and the United States has never been stronger!"

Congressman Brad Sherman hailed Modi's re-election and congratulated "the world's most populous democracy" for holding "another successful election".