CAIRO -- Egypt´s Muslim Brotherhood will back the organization´s former deputy head and chief financier in the race for Egypt´s presidency, accelerating the powerful Islamist group toward a possible collision with the country´s interim ruling military regime that threatens to undermine Egypt´s tense transition to democracy.

Mohamed Badie, the Brotherhood´s head or General Guide, told reporters on Saturday night that Khairat Al Shater, 62, had submitted his resignation from the group in order to pursue the presidency in elections that begin on May 23.

The Brotherhood´s move is the latest salvo in its recent confrontation with a lameduck military leadership that has pledged to yield its power to an elected president by the end of June.

Mr. Badie and other senior Muslim Brotherhood figures made no secret that their endorsement of Mr. Al Shater was meant as a rejoinder to the Supreme Council of Armed Forces, or SCAF, the council of generals who have clung to the levers of executive power in Egypt´s government even after the election of a Brotherhood-dominated parliament in January.

Without directly accusing the military of trying to frustrate Egypt´s transition to democracy, Mahmoud Hussein, the deputy head of the group, said "threats to the revolution" compelled the organization to nominate one of its own. Mr. Hussein said the SCAF had done too little to yield control.

Mr. Hussein said the SCAF had threatened to dissolve Egypt´s Islamist- dominated parliament and refused to dismiss the military-appointed cabinet and allow parliament to nominate its own ministers.

The Brotherhood has repeatedly accused the cabinet, which is led by former Prime Minister Kamal Al Ganzouri, of making a hash of Egypt´s political transition while doing little to reverse the country´s cratering economy.

The Brotherhood leadership seemed to acknowledge that their endorsement of Mr. Al Shater would rattle liberals and the military by expanding the group´s claims on political power to nearly all elements of Egypt´s emerging democracy, including the parliament, the presidency and the body charged with writing Egypt´s new constitution.

"The Freedom and Justice Party confirms that it is not seeking power for the sake of fame, but to achieve its larger objectives which are to please God, comprehensive reform and meeting the goals and objectives of the revolution," said Mr. Hussein.

Mr. Hussein said Mr. Al Shater´s candidacy will present a popular bulwark against several candidates who enjoy the backing of the former regime. Mohamed Morsi, the chairman of the Brotherhood´s Freedom and Justice Party, also thanked the military for securing Egypt during a sensitive moment in its history.

Mr. Al Shater spent more than a decade in prison under the previous regime for his financial backing of the once illegal Brotherhood. His previous convictions for membership in the Brotherhood -- which was illegal under President Hosni Mubarak who was ousted last February -- could still prevent him from running for president under Egyptian law.

Mr. Morsi told reporters on Saturday that the military had already cleared Mr. Al Shater of all charges. Military officials could not be reached for comment.

In selecting Mr. Al Shater, the Brotherhood is effectively challenging the military to pardon Mr. Al Shater´s conviction or confront the Brotherhood´s legions of members and supporters. The military pardoned Ayman Nour, another prominent dissident politician under the previous regime, earlier this week.

The Brotherhood and their partners among ultra-conservative Salafi Islamists have on rare occasions used street protests to press their demands over the past year. During at least three Brotherhood-led protests in the past year, the organization has rallied huge shows of force by bringing out enormous numbers.

Mr. Al Shater has long enjoyed a reputation as one of the most powerful members in the 84-year old organization. A multimillionaire businessowner with interests in textiles and furniture, Mr. Al Shater has spent a fortune financing the Brotherhood´s political and public service operations.

It´s unclear what an Al Shater presidency would look like but his political background has shown a tendency toward hardline religious conservatism and a market-oriented business savvy.

The Brotherhood´s decision to back one of its own members marks the latest reversal of the Islamist group´s previous commitments that it would not use its well-established popularity to dominate the first elected government in post-revolutionary Egypt.

Mr. Al Shater´s largely symbolic resignation from the Brotherhood allows the group to hew to its earlier pledges that it would not field a candidate.

But activists have noted that the Brotherhood reversed previous pledges meant to reassure anxious liberals and observers in the West that the group intended to check its own formidable political power.

Last year, the group said it would only field candidates in a limited number of constituencies in parliamentary elections. But the group´s political party ended up posting candidates -- sometimes more than one -- in almost all of Egypt´s parliamentary constituencies.

Liberal and secular-minded activists were also outraged last week when politicians and intellectuals from the Brotherhood and Salafi political parties dominated a constituent assembly that will be charged with drafting Egypt´s next constitution.

Religious conservatives had said that the constitution drafting process would be inclusive of a variety of political voices despite Islamists´ strong presence in parliament.

The Brotherhood´s backing will leapfrog Mr. Al Shater from the shadows of the secretive group´s upper leadership to frontrunner status in a hotly contested presidential race that is so far dominated -- and perhaps split -- by Islamist candidates of varying hues of conservatism.

While electoral polls in Egypt are rare and somewhat unreliable, anecdotal evidence shows that the secular-minded Amr Moussa, the former secretary general of the Arab League, may still be Mr. Al Shater´s primary competitor.

But prominent Islamist leaders have made strong showings at rallies over the past several weeks.

Liberal activists as well as many young Islamists have rallied behind Abdel Moneim Aboul Fotouh who was a leading reformist voice within the Muslim Brotherhood before the group expelled him last summer.

He is challenged by Hazem Salah Abu Ismail, a deeply conservative Islamist intellectual who enjoys support from within both the Brotherhood and Egypt´s loosely-joined Salafi community. Write to Matt Bradley at matt.bradley@dowjones.com (Copyright © Dow Jones & Company, Inc.) 04/01/12)