CAIRO, Egypt — Activating its powerful clout and organization, the Muslim Brotherhood turned out millions across Egypt Saturday in support of President Mohammed Morsi, a show of strength that suggested the challenges facing those who accuse the president of granting himself dictatorial powers one day ahead of a critical court decision.

The demonstrations coincided with Morsi's announcement that he had signed off on a hurriedly drafted constitution and set Dec. 15 for a countrywide referendum on the document — even though the country's constitutional court might rule Sunday that the Brotherhood-dominated constitutional assembly that wrote the document had been constituted illegally.

"This is the first time in our nation's history an elected assembly drafts the constitution," Morsi declared. "I am calling for Egyptians to vote for the new constitution."

How the court will decide and whether there was any mechanism to enforce its decision if it overturns Morsi's actions were unanswered questions, made more critical by the outpouring of support shown in Brotherhood rallies in Cairo and Alexandria, Egypt's two largest cities, and other locations around the nation. The turnout dwarfed by many multiples the anti-Morsi protests held in recent days.

State television used split-screen technology to broadcast scenes from the massive pro-Morsi rallies as it showed the comparatively meager remnants of an anti-Morsi rally held Friday in Cairo's Tahrir Square. The technique emphasized the difference in the size of the crowds the Brotherhood could turn out and those generated by the secularists, liberals and Christians who oppose Morsi's most recent decree, when he exempted his declarations from court oversight.

The contrast was undeniable — and not just in numbers. The protests Saturday were filled with bearded Islamists and conservative women, many from poorer neighborhoods. Those who came to Tahrir on Friday clearly represented the nation's upper class, with unveiled women and clean-shaven men.

Both sides claim to represent the demands of the "revolution," Egyptian shorthand for the 18 days of protests nearly two years ago that ended when the Egyptian military pushed then President Hosni Mubarak from power and then governed the country itself until Morsi took the oath of office five months ago.

Developments since have only solidified the divide as this nation searches to define itself after decades of dictatorial rule that included the suppression of the Brotherhood. One man walking through the protests in support of Morsi on Saturday was overheard telling a friend, "Of course, Tahrir is full of people smoking and loose women. Thank God, we Muslims are united."

Saturday's protests were a reminder of the Brotherhood's mastery of political organization.

At Cairo University, where the capital's pro-Morsi rally was held, hundreds of thousands of people converged, brought from around the country by tour buses that lined the streets. Only 24 hours after the constitutional assembly hastily passed the draft constitution, supporters were already donning headbands that read "Yes to the constitution."

Ralliers carried professionally made signs in support of Morsi, often with the same slogans. "We love you Morsi," many read, and "The people support the president's decisions." Like clockwork, a pickup truck configured with speakers drove through the crowds, leading them in chants that denounced the Mubarak-appointed judges. "No No to remnants, Yes Yes to the Constitution," the ralliers cried in a phrase that rhymes in Arabic.

The current tumult in Egypt was triggered by a seven-point decree Morsi issued Nov. 22 in which he declared that his decisions were no longer subject to judicial oversight. Morsi said the change was necessary measure to prevent Mubarak holdovers from thwarting needed reforms. But the move drew outrage from many, including some members of Morsi's government, who accused Morsi of grabbing power in anticipation of Sunday's court ruling.

The courts vowed to rule anyway. In what appeared to be an effort to make the ruling irrelevant, the assembly hastily passed the 234 articles that make up the constitution in an all-night session that ended just before 7 a.m. Friday.

Until Saturday, the anti-Morsi protests had seemed huge, gathering hundreds of thousands in Tahrir. Some of Egypt's most recognized public figures joined the protests, including Mohammed ElBaradei, the former head of the International Atomic Energy Agency, as well as failed presidential candidate Hamdeen Sabahi, who finished third in voting last summer.

But the pro-Morsi rallies — the first held since Nov. 22 — were a bracing reminder of the Brotherhood's political capabilities. In interviews, the Morsi supporters spoke in seeming unison about why there were there, voicing support for Morsi's decree and the new constitution, often in the same language.

"The constitution will bring back stability," said a woman, 25, who only wanted to be referred to by a nickname, Umm Zaineb, or mother of Zaineb.

Just as in the parliamentary elections last year, and presidential elections earlier this year, the Brotherhood demonstrated its ability to get out the vote, often from people who believed Islam was under attack from liberals and secularists. Among the chants people yelled Saturday was "With our blood and our soul, we will defend Islam."

It also was clear the Brotherhood intends to fight the upcoming referendum on religious terms, something that will inflame opponents as well, who say that the proposed constitution does not represent the mosaic of Egyptian voices that includes a large Christian population. The crowd seemed particularly focused on the proposed Artice Two, which calls for Egyptian laws to be based on the "principle of shariah" Islamic law.

"First of all, the constitution has not passed yet, and there is a current that rejects it," said Rashia el Zamoran, 20, a secretary from Cairo. "They say shariah does not treat men and women equally, that this is a flaw with shariah. We want to prove this is not true."

Morsi has refused to back down on his decree. In an interview with Time magazine published earlier in the week, he said he believed that Egyptians supported his exempting himself from judicial oversight. "I think you have seen the most recent opinion surveys — I think more than 80 percent, around 90 percent, of the people in Egypt are, according to these opinion measures, they are with what I have done. It's not against the people, it's with the people."

Liberals have vowed to fight on, though it is unclear what they can do to force Morsi's hand. The country's military, so critical to Mubarak's departure, has shown no interest in inserting itself in the struggle, with the proposed constitution notably granting it enormous autonomy from governmental oversight.

One question does remain, however: Who will oversee any referendum on the constitution? Judges traditionally have assumed that role, but many are on strike to protest Morsi's constitutional declaration.

Amina Ismail is a McClatchy special correspondent. Visit the McClatchy Washington Bureau at Distributed by MCT Information Services.