CAIRO >> Thousands of Egyptians took to the streets after Friday midday prayers in rival rallies and marches across Cairo, as the standoff deepened over what opponents call the Islamist president’s power grab, raising the specter of more violence.

President Mohammed Morsi responded to bloody clashes outside his palace with a fiery speech denouncing his opponents, deepening the crisis. The opposition turned down his appeal for talks, saying the president had not fulfilled their conditions for beginning negotiations.

Protesters are demanding that Morsi rescind decrees that give him almost absolute power and push an Islamist-friendly constitution to a referendum on Dec. 15. The decrees sparked a crisis that has boiled for more than two weeks. Demonstrations have reached the size and intensity of those that brought down President Hosni Mubarak early last year.

In a televised address late Thursday, an angry Morsi refused to call off the vote on the disputed constitution. He accused some in the opposition of serving remnants of Mubarak’s regime and vowed he would never tolerate anyone working for the overthrow of his  government.

He also invited the opposition to a dialogue starting Saturday at his palace, but he gave no sign that he might offer any meaningful concessions. Morsi’s opponents replied they would not talk until Morsi cancels his decrees.

The president’s remarks were his first comments to the public after bloody clashes outside his palace on Wednesday, when thousands of his backers from the Muslim Brotherhood fought with the president’s opponents. Six people were killed and at least 700 injured.

The speech brought shouts of “the people want to topple the regime!” from the crowd of 30,000 Morsi opponents gathered outside his palace — the same chant heard in the protests that brought down Mubarak.

Since the crisis erupted, the opposition has tried to forge a united front. The squabbling groups created a National Salvation Front to bring them together, naming Nobel laureate Mohamed ElBaradei, the country’s top reform campaigner, as its leader.

Speaking on the new umbrella group’s behalf, ElBaradei responded to Morsi’s speech in his own televised remarks, saying that Morsi’s government showed reluctance in acting to stop Wednesday night’s bloodshed outside the palace. He said this failure has eroded the government’s legitimacy and made it difficult for his opposition front to negotiate with the president.

ElBaradei said Morsi has not responded to the opposition group’s attempts to “rescue the country” and that the president had “closed the door for dialogue” by “ignoring the demands of the people.”

After Friday prayers, protesters began marching to the palace from several different directions.

The April 6 movement, which played a key role in sparking the uprising against Mubarak, called its supporters to gather at mosques in Cairo and the neighboring city of Giza to march to the palace. They termed Friday’s march a “red card” for Morsi, a reference to a football referee sending a player off the field for a serious violation.

Egypt’s military intervened on Thursday for the first time, posting tanks around the palace and stringing barbed wire.

Also on Friday morning, thousands of Brotherhood members gathered in Cairo outside the mosque of Al-Azhar, Egypt’s most respected Islamic institution, for the funeral of two members of the fundamentalist group who were killed during Wednesday’s clashes.

During the funeral, thousands Islamist mourners chanted, “with blood and soul, we redeem Islam,” pumping their fists in the air. “Egypt is Islamic, it will not be secular, it will not be liberal,” they chanted as they walked in a funeral procession that filled streets around Al-Azhar mosque.  

Ultraconservative Islamists known as Salafis are organizing their own rally Friday against what they say is biased coverage of the crisis by private Egyptian satellite TV channels.