SYDNEY, Aug 20 (Reuters) - Voter support for Australian Prime Minister Malcolm Turnbull crashed to its lowest level since December, an opinion poll published on Monday showed, further stoking leadership speculation in his ruling centre-right coalition.
The Ipsos poll published in Fairfax newspapers shows Turnbull's personal approval plunging nine points to 46 percent, just as he is struggling to unite a restive party room over energy policy.
Although Turbull is still personally more popular than opposition Labor leader Bill Shorten, the poll shows support for his Liberal-National coalition fell four points to 45 percent, 10 points behind Labor and enough for a crushing electoral defeat.
It is the widest gap between the parties in 17 months and with an election due before May, it has deepened speculation that Turnbull - who himself ousted his predecessor as party leader because of poor polling - could face an open challenge.
Media reported government members were being sounded about support for a challenge to Turnbull's leadership, with Home Affairs minister Peter Dutton seen as the most likely potential challenger, although ministers tried to downplay talk of division.
"I don't believe that there'll be a challenge to Malcolm Turnbull's leadership, I believe that the cabinet is 100 percent behind Malcolm Turnbull, including Peter Dutton," Minister for Defence Industry Christopher Pyne told reporters in Canberra.