Egypt's Muslim Brotherhood will not take part in an interim Cabinet to replace the administration of ousted President Mohammed Morsi, a spokesman for the group said Wednesday, spurning an offer from the new prime minister to form a broad-based government to shepherd the country through a transition period.

New Prime Minister Hazem el-Beblawi, who was appointed by the interim president on Tuesday, is holding consultations on a Cabinet that will face the difficult task of guiding the deeply divided country through what promises to be a rocky transition period following the military's toppling of Morsi last week. In what is seen as an attempt at reconciliation, el-Beblawi has said he will offer the Brotherhood, which helped propel Morsi to the presidency, posts in his transitional government.

A Brotherhood spokesman said the group will not take part in an interim Cabinet, and that talk of national reconciliation under the current circumstances is "irrelevant." He spoke on condition of anonymity because of concerns for his security.

Egypt's country's interim leaders and military have tried to fast-track the transition process in an effort to restore a measure of stability to the country while also reassuring the U.S. and other Western allies that the country is on a path toward democratically-based leadership. Under a timetable announced by the interim president, new elections are to be held early next year.

The Brotherhood's refusal to join the new military-backed leadership was widely expected. The group has denounced the toppling of Morsi as a coup against democracy, and has vowed to continue its street protests until the deposed president is returned to power.

Still, its rejection underscored how polarized the nation's politics have become, and laid bare the monumental task the interim leadership faces in trying stabilize the country. The nascent government will soon face demands that it tackle economic woes that mounted under Morsi, including fuel shortages, electricity cutoffs and inflation.

Saudi Arabia and the United Arab Emirates provided a welcome boost for the new leadership on Tuesday. The two countries, both opponents of Morsi's Brotherhood, celebrated his ouster by showering the cash-strapped Egyptian government with promises of $8 billion in grants, loans and badly needed gas and oil.

In doing so, they are effectively stepping in for Morsi's Gulf patron, Qatar, a close ally of the Brotherhood that gave his government several billion in aid. During Morsi's year in office, he and his officials toured multiple countries seeking cash to prop up rapidly draining foreign currency reserves and plug mounting deficits _ at times getting a cold shoulder.

As the new prime minister looks to cobble together a government, Egypt's new leadership is facing pressure from those who backed the military's move against Morsi.

Several groups in the loose coalition participating in the political process were angered over the transition plan issued Monday by interim President Adly Mansour. His declaration set out a seven-month timetable for elections but also a truncated, temporary constitution laying out the division of powers in the meantime.

At the heart of liberals' objections to the plan is that they wanted to write a new constitution, not amend the one written under Morsi by an Islamist-dominated panel. That constitution contained several articles that drew fierce criticism from liberal quarters, and helped sparked street protests and violence in 2012.

The top liberal political grouping, the National Salvation Front, rejected the transition plan late Tuesday. It said it was not consulted _ "in violation of previous promises" _ and that the declaration "lacks significant clauses while others need change or removal." It did not elaborate but said it had presented Mansour with changes it seeks.

The secular, revolutionary youth movement Tamarod, which organized last week's massive protests against Morsi that prompted the military to step in, also criticized the plan, in part because it gives too much power to Mansour, including the power to issue laws. A post-Morsi plan put forward by Tamarod called for a largely ceremonial interim president with most power in the hands of the prime minister.

Egypt remains deeply polarized with heightened fears of violence, especially after the killing Monday of more than 50 Morsi supporters outside a military building in Cairo. The Brotherhood and Islamist allies say they are under siege by a military crackdown that has jailed five of their leaders and shut down their media outlets.