If dumped Mrs Roy would be set to lose her ministerial positions in the National-led government.
ACT MPs were tight-lipped as they arrived for their weekly meeting. Waiting journalists were then removed from the floor of Bowen House where the meeting was taking place.
Mrs Roy, Minister of Consumer Affairs and an associate minister of defence and education, had with fellow MP Sir Roger Douglas been trying to remove Rodney Hide as leader.
ACT has only five MPs, and would not be in Parliament but for Mr Hide winning the Epsom electorate in the 2008 election -- the party won only 3.65 percent of the vote, below the 5 percent threshold required to win seats in Parliament without an electorate.
Mr Hide and Mrs Roy are ministers in the National-led Government.
Prime Minister John Key has said he would not have Sir Roger as a minister, so John Boscawen could pick up Mrs Roy's No 2 position, and at least some responsibilities as a minister outside Cabinet.
David Garrett is the other ACT MP.
The challenge was believed to be sparked by controversy over the international travel costs of Mr Hide's partner, and negative remarks he made about the prime minister -- both of which he apologised for.
