One of Donald Trump’s biggest but least known donors has said she does not support all of his tweets after going public with her political views.

Rebekah Mercer, the previously publicity-shy daughter of billionaire Robert Mercer, wrote a piece in the Wall Street Journal to counter “sensational fantasies” and long-running speculation about her political views.

She insisted she was pro-immigration, rejected any form of discrimination as “venomous and ignorant” and added she was a believer in the importance of science.

Ms Mercer also confirmed she had become disillusioned with how Steve Bannon, the former Trump campaign chief, was running Breitbart News, a right-wing political website in which she owns a minority stake. He departed last month after a public row with Mr Trump.

The article from Ms Mercer, whose family has reportedly spent tens of millions of dollars backing Republican candidates since 2010, marks a rare public statement.

Her family’s backing of Mr Trump and more hardline factions in the party as well as their reluctance to speak in public has fuelled speculation about what they believed.