Nikki Haley, a former South Carolina governor and United Nations ambassador, has announced she is a candidate to become US president in 2024.
She is the second major Republican candidate to run, after ex-boss Donald Trump launched his bid in November.
She said in 2021 she wouldn’t challenge him for the White House, but changed her mind in recent months, citing the need for “generational change”.
Ms Haley is the third Indian American to seek a presidential nomination.
Other Republicans expected to launch campaign to be selected for their party include Florida Governor Ron DeSantis and former Vice President Mike Pence.
She has previously criticised Mr Trump’s behaviour up to and during the 6 January 2021 attack on the US Capitol by his supporters.
The day after the riot, she said in a speech that “his actions since election day will be judged harshly by history”.
Most early polls show Mr Trump with a comfortable lead in South Carolina, whose primary he won on his way to the presidency in 2016 – an indication of the uphill battle the former ambassador will have, even on what should be friendly ground.
A recent survey by the polling firm Trafalgar Group that included current and likely candidates has Mr Trump in first place with 43% and Ms Haley in fourth at 12%.
Other Indian Americans to run before her were Louisiana Governor Bobby Jindal, whose bid in 2015 never gained significant traction, and current Vice-President Kamala Harris, who sought the 2020 nomination.