During her recent visit to the US, Ramphele said she was collecting money for a political party and said she was "entering politics to save her country", the Rapport said on Sunday.
She also rallied support from ambassadors.
Ambassador to Argentina and former Democratic Alliance (DA) leader Tony Leon said two people at Ramphele's meetings in America confirmed this, he told the City Press.
DA leader Helen Zille tried to get Ramphele to join her party last year, but she declined and formed the Citizens' Movement, a non-governmental organisation. She said at the time that she had never joined a political party in her life.
"I am not a joiner but a change agent. I have always seen my role as a change agent supporting any appropriate transformative process initiated by any South African," she said.
According to Sunday's report, Ramphele thought stronger opposition was needed after President Jacob Zuma was re-elected ANC president at the party's elective conference in Mangaung in December.
Ramphele was not available to comment on Saturday. She was expected to make an announcement soon.
'No Sunday picnic'
The ANC has in the past dismissed her criticism of the ruling party as opposition politicking.
ANC secretary general Gwede Mantashe said at the time her comments were an indication of her intention to enter active politics. "If she wants to join the DA or form a political party, she will soon find out that it is no Sunday picnic," he added.
Ramphele cut her teeth as an apartheid activist while studying medicine at the University of Natal in the 1970s. She became increasingly involved in student politics and was one of the founders of the Black Consciousness Movement, alongside Steve Biko. She was specifically involved in organising and working with community development programmes through the movement.
In 1975, she founded the Zanempilo Community Health Centre in Zinyoka, in the Eastern Cape – one of the first primary health care initiatives outside the public sector in South Africa.
Due to her political activities, she was banished to the town of Tzaneen from 1977 to 1984 by the apartheid government. – Additional reporting by Sapa