Opposition in the Lok Sabha, is significant because she is herself seen as a frontrunner for the mantle and has in the past only given lukewarm support to Modi.
She told reporters on Modi’s campaign trail in Vadodara that the Gujarat strongman, who is seeking his third term at the helm of the state, is “a competent and proper leader to be the prime minister of India”.
Swaraj has never spoken openly about the possibility of Modi for the top slot, let alone endorse his candidature.
In fact, two years ago, she had said, “Modi’s magic and charisma have worked in Gujarat but it is not necessary that everybody’s magic works at every place.”
Her latest statement has come a week after her counterpart in the Rajya Sabha, Arun Jaitley, had said, "since so many leaders have campaigned in Gujarat, it indicates that the entire BJP is behind Modi. We are here to give our party a historic victory”.
All eyes within the BJP are on Modi and the strong possibility of an enhanced role for him in the event of a massive win in Gujarat, which goes to the polls on December 13 and 17.
In apparent preparation for a larger role at the Centre, the man himself has been focusing on national issues in his campaign speeches, blaming the Congress-led UPA for the country's ills.
A big win could force the BJP leaders as well as the party's ideological patron, the Rashtriya Swayamsevak Sangh (RSS), to respond to pressure from the rank and file to project him as the party's candidate for PM, BJP insiders say.
Swaraj's praise for Modi could also be prompted by intricate party politics, BJP sources say. Modi and Jaitley are close to each other, while Swaraj has often been seen as a strong supporter of BJP patriarch LK Advani, who at 85 is viewed by many as lacking the steam to lead the party in the future. Falling in behind Modi would bring Swaraj closer to the RSS, which favours a bigger role for him.
However, Modi's handicap is that he is not acceptable to key allies of the NDA like Bihar chief minister and Janata Dal (United) leader Nitish Kumar.
He is seen by them as one of the country's most divisive figures, with a question mark hanging over him from the 2002 communal riots in Gujarat that killed 1,000 people, most of them Muslims.
Last year, instead of ordering a case against him, the Supreme Court sent back to a local court a special investigation team report on accusations against Modi, a development Modi hailed as a clean chit.
The court's move was also welcomed by Sushma, who said then that Modi had "overcome all his obstacles, his setbacks and cleared his agnipariksha".