THE National Party is promising to double the baby bonus for stay-at-home mothers if the Coalition wins the federal election.The promise will be made today at the party’s federal conference in Canberra where much opposition is expected over Coalition paid parental leave policy.The Nationals oppose paid parental leave on the grounds it discriminates against stay-at-home parents who receive the lesser-paying baby bonus.Today’s policy promise is designed to help mollify those concerns and help avoid embarrassing debate at the conference.This week, the Senate passed the Rudd government’s historic universal paid parental leave scheme which, from January 1, will pay all parents who stay home the minimum wage of $570 a week for 18 weeks. This is worth twice the baby bonus which is paid in 13 fortnightly instalments.The Nationals’ promise, which would cost an extra $1.36 billion, would create a new allowance that would be paid in 13 fortnightly instalments at double the rate of the baby bonus.The Nationals would still have to convince the Liberal Party to adopt the payment as policy.The Opposition leader, Tony Abbott, has already promised that, if elected, he will increase the company tax rate by 1.7 per cent for more than 3200 businesses to fund a universal paid parental leave scheme that would pay parents their full salary – capped at $150,000 – for six months.As Mr Abbott vowed yesterday to push ahead with the policy, the Nationals leader, Warren Truss, said his party would back it, even if members thought it too generous, to ensure Coalition unity.Also today, the Nationals are expected to endorse a motion opposing Mr Abbott’s policy promise to hold a referendum for a federal takeover of the Murray-Darling Basin.