While the leave scheme would not start until July 1, 2015, Liberals say Mr Abbott plans to introduce legislation to establish it as early as February 2014, raising the prospect of negotiations with the Greens in the Senate. Tony Abbott takes on parental leave. Credit:Andrew Meares The policy was first announced in 2010 and would see some high-earning new mothers on annual salaries of $150,000 and above, paid up to $75,000 over six months following the birth of a baby. But the $5.5 billion-a-year scheme is bitterly opposed by some in the Coalition. Nationals are most hostile, arguing the policy favours already well-off women. According to one MP, a number of senators who already felt disaffected by the fact it was announced without reference to the party-room, are describing the looming debate as a ''line in the sand'' issue that is likely to be used to protest over the general direction of government policy.

With a febrile atmosphere behind the scenes, one MP said Mr Abbott should forget about negotiating with the Greens or Labor over the leave scheme, because some of his own senators could cross the floor. And Senator John Williams told Fairfax Media on Thursday that he would cross the floor if he did not like the paid parental leave legislation. ''I'll make that decision when I see the fine detail. I, along with some others, are not over keen to see this cost put in at this stage. Yes, I'd be quite happy to cross the floor if I was not happy,'' Senator Williams said. He said the economy was not strong enough to support the multibillion-dollar scheme. The warning comes as disquiet grows in Coalition ranks over what right-aligned MPs believe is an aversion to any policy that is not consistent with the populist agenda of certain powerful ''moderates'' with the Prime Minister's ear.

Right-aligned MPs have renewed a complaint that Mr Abbott relies principally for counsel on people from the ''moderate'' end of the Liberal Party, dating back to Malcolm Turnbull's shadow cabinet of 2009. Loading One said it had not escaped notice that apart from Mr Abbott himself, his inner circle contained ''a bunch of moderates'', including Ms Credlin, Julie Bishop, Joe Hockey, Christopher Pyne, George Brandis, and Greg Hunt. Conspicuously absent from the group is Senate leader, Eric Abetz. The right-aligned Tasmanian has been described by a colleague as ''closed out''.