Tensions have risen between Ms Bishop on the one hand and Mr Hockey on the other with the Treasurer's depleted political fortunes seen as locked to those of the Prime Minister. Tension rises on frontbench: Joe Hockey and Julie Bishop in Parliament on Monday. Credit:Andrew Meares Ms Bishop, however, is seen as a possible leadership option amid ongoing speculation that the Liberal party room could revisit the issue in the second half of this year if the polls do not improve. Asked for her thoughts about why she rolled her eyes behind the Treasurer, Ms Bishop told reporters on Monday night she would "keep those to myself". "The mention of the expenditure review committee can have a different impact on different people at various times and I just responded to the mention of (it), that's all."

Foreign aid became the biggest single victim of cut-backs in the Coalition's first 18 months in office, Ms Bishop was alarmed to read that an unnamed but apparently well-placed source in the government had flagged a further "small cut" to aid in May. In forceful comments revealing her anger at reading about key elements of her portfolio in a newspaper, Ms Bishop said that she would expect to know about such things as the relevant minister and said she would take the matter up with Mr Hockey. Asked if there was room to cut the aid budget further, Ms Bishop responded, "I don't believe that we do, I believe that we have it about right". While Finance Minister Mathias Cormann moved quickly to defuse the problem by declaring that, as a key member of expenditure review committee, he knew of no plan to make fresh cuts to international aid, the incident has fanned smouldering tensions within the government at the highest levels, revealing an absence of trust among Mr Abbott's most senior leadership group. A source said relations between Mr Hockey and Ms Bishop were at an all-time low and that Ms Bishop's relationship with Mr Abbott was also under strain - largely because of his office.

In Parliament, Ms Bishop, regarded by many Liberals as the government's best performing minister, made no secret of her disdain for Mr Hockey when he praised Malcolm Fraser for initiating the review committee process. The review committee is also known as "the razor gang", for its brutal line-by-line evisceration of departmental spending. Aid advocates were appalled by the prospect of further cuts. Marc Purcell, executive director of the Australian Council for International Development, said that on top of the $11 billion already slashed, any further cut would "wipe out any credibility Australia has on international aid". Mr Purcell, who was leading a delegation from the aid sector to lobby MPs in Canberra on Monday, said Mr Hockey had already shown he had no grasp of the importance aid played in international relations, regional security and helping small neighbours prepare for disasters such as Cyclone Pam. "The poorest people in our region cannot continue to bear the burden of the Treasurer's lack of imagination in solving his budget problems," he said.

After recent cuts, Australian foreign aid spending will reach its lowest level since records began. By 2016-17, it will be just over $3.8 billion, or 0.22 per cent of gross national income. Previously, the Coalition and Labor have committed to raising foreign aid spending to 0.5 per cent of gross national income but have both either delayed or refused to specify a time frame. Australia has also committed to the UN's Millennium Development Goals, which seek 0.7 per cent by 2020. The current spending level compares to 0.47 per cent in 1974-75, 0.44 per cent in 1983-84 and 0.34 per cent in 2012-13. It also compares to the United Kingdom, where the Parliament recently passed a bill fixing foreign aid spending at 0.7 per cent, meeting the UN goal ahead of the deadline. Luxembourg commits 1 per cent, Sweden 1.02 per cent and the United Arab Emirates 1.25 per cent.

As a result of the cuts, Australia will drop from 13th to 19th in the OECD's 28-member foreign aid donor group. Mr Purcell said his organisation was encouraged by Ms Bishop's comment that she would take the issue up with Mr Hockey, and urged her to "fight hard against any further cuts to aid and development funding". With David Wroe and Fergus Hunter Follow us on Twitter