Deloitte has told partners that chief executive Cathy Engelbert has not been renominated for a new term, touching off a behind-the-scenes leadership dispute at the Big Four accounting firm.

Engelbert, the first woman to run one of the Big Four firms in the US, is three-plus years into a four-year term as Deloitte’s CEO. But Deloitte’s US partners were told in a recent email that she was not being renominated for a second term at this time as the firm begins its every-four-years CEO-election process, according to people familiar with the matter.