Graham Brady, chairman of a powerful party rules committee, said Wednesday the body had decided not to change the rule that a party leader can only face one no-confidence vote in a year.
Pro-Brexit Conservatives are angry with May's failure to take Britain out of the European Union, almost three years after voters backed leaving. They want her replaced with a more staunchly pro-Brexit leader.
But May survived a Conservative no-confidence vote in December, leaving her safe for 12 months.
May says she'll step down once Parliament has approved a Brexit deal.
Brady said, however, that May must provide more clarity about her departure and provide "a clear roadmap forward."
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