Malcolm Turnbull has seized the Liberal leadership from Brendan Nelson after winning this morning's party room ballot by 45 votes to 41.

Julie Bishop was unopposed and will remain as deputy leader.

Dr Nelson called the spill late yesterday in a move designed to surprise Mr Turnbull, who had been on holiday in Italy last week.

Dr Nelson has held the leadership since last November, when he won the job in a vote against Mr Turnbull by 45 votes to 42.

Dr Nelson's supporters say they are disappointed but will now back Mr Turnbull, who now becomes the third Liberal leader in less than a year.

Liberal Senate leader Nick Minchin says he will support Mr Turnbull as leader, even though he voted for Dr Nelson.

Senator Minchin says Dr Nelson was not given enough time to prove his leadership abilities.

"I thought he deserved to have more time to try to establish his credentials and his authority as leader, but I respect the majority will of the party," he said.

Prime Minister Kevin Rudd has congratulated Mr Turnbull and says he looks forward to working with him on national challenges, especially Australia's move towards a republic.

Meteoric rise

The ascension to the leadership caps Mr Turnbull's meteoric rise through the Liberal ranks.

He came into parliament four years ago after winning the inner Sydney seat of Wentworth.

He has been a journalist, barrister and a merchant banker in previous careers and was well known as the face of the republican movement.