NEW DELHI - India's Prime Minister Narendra Modi congratulated US President-elect Joe Biden and also referenced Vice-President-elect Kamala Harris' South Asian roots, noting it was a day of pride for all Indian Americans not just her "chittis" or aunts.

"Congratulations @JoeBiden... on your spectacular victory! As the VP, your contribution to strengthening Indo-US relations was critical and invaluable. I look forward to working closely together once again to take India-US relations to greater heights," tweeted Mr Modi on Sunday.

Mr Biden, as vice-president and as a long-time member, including the chairman, of the Senate Foreign Relations Committee, has been a strong proponent of closer India-US ties and a key supporter of the India-US civilian nuclear deal, which was finalised in 2006 and helped elevate ties between the two countries.

There has also been much interest and curiosity in Ms Harris, whose aunt and uncle - Dr Gopalan Balachandran and Dr Sarala Gopalan - live in India.

Mr Modi specifically referred to her "chittis", which means aunts in Tamil.

Ms Harris, while accepting the Democratic nomination for vice-president in August, had spoken of her Tamil-origin mother, Ms Shyamala Gopalan, and her "chittis,", creating much excitement among Tamilians everywhere. She also mentioned her mother in her speech Sunday.

"Your success is pathbreaking, and a matter of immense pride not just for your chittis, but also for all Indian Americans. I am confident that the vibrant India-US ties will get even stronger with your support and leadership," tweeted Mr Modi, who has a lot of support within the Indian American community in the US.

The rest of the Indian leadership also extended congratulations to the Democrat winners in an election that was closely followed in India where interest was much piqued by the fate of US President Donald Trump whose rapport with Mr Modi has been a major talking point.

On Twitter, "HowdyModi" trended in the morning with "NamasteTrump", along with "Joe Biden".

Howdy Modi and Namaste Trump were the two massive rallies, held in the US and India respectively, where Mr Modi shared the stage with Mr Trump. Both events had faced criticism within India of going against the tradition of bipartisan support for India-US ties within the American polity.

Congress leader Rahul Gandhi extended his congratulation to Mr Biden and his message of unity.

"I'm confident that he will unite America and provide it with a strong sense of direction," tweeted Congress leader Rahul Gandhi, adding: "It makes us proud that the first woman to serve as Vice-President of the USA traces her roots to India."

Congress president Sonia Gandhi said in a statement: "India looks forward to a close partnership that will be beneficial to peace and development in our region and around the world."

Joining in, another Congress leader Shashi Tharoor tweeted: "All Indian democrats will echo this sentiment as we join @RahulGandhi in applauding @JoeBiden & @KamalaHarris. On a personal note, delighted to have a US V-P who enjoys idlis and makes dosas!" he tweeted.

The upward trajectory of India-US ties and the American desire to see India in a stronger strategic embrace is expected to continue.

Ties are anchored in expanding defence cooperation and the mutual distrust and worries over the rise of China.

A lot of focus in India will also be on how the Biden presidency deals with Pakistan and China apart from handling the Afghan peace process, all of which has an impact on India.

Analysts said that the trajectory of India-US ties will not change under the new presidency.

"There is going to be quite a bit of bipartisan approach for ties with India because I think over the last four years a lot of changes have taken place in terms of China. I think when it comes to China, it is the strategic glue between India and the US, and that will remain for some time to come," said Dr Rajeshwari Pillai Rajagopalan, a distinguished fellow at the Observer Research Foundation, a New Delhi-based think tank

"There will be some hiccups not just on trade issues but there could be issues around freedom of press, human rights issues violation and Jammu and Kashmir. There are going to be tricky issues but because of China factor, this might be handled better."

India had seen protests over the introduction of the Citizenship Amendment Act, which critics have seen as going contrary to the secular traditions of the country as it provides religion-based citizenship for minorities in Muslim majority neighbouring countries.

"We have a new reality. We have a Democrat in power. We (India) will find ways to work. There will be continuity from Obama-Biden team. Many familiar faces and India will be able to reconnect and rebuild those ties."

Concern remains within India on whether Mr Biden will speak out on domestic issues, largely ignored by Mr Trump. The Democrats have traditionally spoken out on issues related to human rights and Kashmir.

Mr Brahm, a Chellaney strategic thinker and commentator, tweeted: "India has traditionally resented foreign interference in its domestic matters. But Biden, in his official campaign page for Muslim voters, has already slammed Modi's government on issues like Kashmir and citizenship law. In office, he may be more cautious."