More than 22 senators have agreed to join the Friends of India Caucus in the 100-member US Senate.
The caucus will be formally launched on April 29 to promote Indian interests.
Republican Senator John Cornyn and Democratic Senator Hillary Clinton will co-chair the caucus, according to Sharad Lakhanpal, president, American Association of Physicians of Indian Origin.
It is the first time that a country-specific caucus has been formed in the senate, Lakhanpal said in a letter to Prime Minister Atal Bihari Vajpayee, informing him of the senators' decision.
Besides, he said, the caucus now has 184 members, making it the largest.
AAPI, with a countrywide membership of over 50,000 doctors, is considered the one of the most powerful and influential Indian-American organisations.