A major Egyptian opposition group amplified its condemnation of the United States on Saturday, accusing it of being partner to a conspiracy to keep President Mohamed Morsi in power, a day after an American bystander was killed during clashes here.

“America and the Brotherhood have united to bring down the Egyptian people,” said Hassan Shahin, a member of the Tamarod, or “rebel,” movement, referring to the Muslim Brotherhood, which backs Morsi. Shahin spoke during a Saturday press conference staged to rally the support of Egyptians ahead of mass nationwide protests on the one-year anniversary of Morsi’s term in power.

Thousands of Egyptians took to the streets in competing protests for and against the nation’s Islamist president Friday, ahead of the planned anti-government demonstrations on Sunday that many Egyptians are convinced will turn deadly.

By Saturday, clashes that erupted between the rival sides in the coastal city of Alexandria had left three dead and more than 200 wounded, and attackers in Nile Delta cities had set fire to offices belonging to the president’s supporters in the Muslim Brotherhood.

On Saturday, the State Department confirmed that Andrew Pochter, an American, had been killed in Alexandria during the clashes there Friday.

This undated photo provided by the Pochter family shows Andrew Driscoll Pochter. The U.S. State Department confirmed Saturday that the Kenyon College student died Friday, June 28, while photographing clashes between opponents and supporters of President Mohamed Morsi in Alexandria, Egypt. (AP)

Hilary Rosen, a family friend, forwarded a statement from the family that said Pochter, a 21-year-old college student from Chevy Chase, was in Alexandria for the summer to teach English and to improve his Arabic. According to the statement, Pochter appeared to have been stabbed by a protester.

Rosen said Saturday that it was not clear whether Pochter was watching the protests or not at the time but reiterated that he was not involved. “He was definitely not a protester,” she said.

The Egyptian activist group, Tamarod, a chief organizer of Sunday’s rallies, claimed Saturday that it had gathered 22 million signatures in a petition of no confidence for Morsi. It was impossible to verify that number, and the group provided no details.

Ten non-Islamist members of the Islamist-dominated upper house of parliament also used the news conference as an opportunity to announce their resignation, in solidarity with the weekend’s protests.

Activists in the audience interrupted the conference with cries for Morsi’s downfall. “Build the walls around your palace higher. Tomorrow the revolution will wipe you away,” they chanted to the president.

On Friday, the State Department advised against nonessential travel to Egypt and authorized the departure of a “limited” number of nonessential embassy personnel and family members. The U.S. Embassy said it would be closed Sunday, typically a working day in Egypt.

President Obama discussed the unrest during a news conference in Pretoria, South Africa, on Saturday. “The United States supported democracy in Egypt. It’s been challenging given there has not been a tradition of democracy in Egypt,” he said. “Our most immediate concerns have to do with our embassies and consulates. We’ve been in direct contact with Egypt’s government and undertaken a range of planning to make sure we keep our embassies and consulates protected and our diplomats and personnel there safe.”

In Cairo’s Tahrir Square on Friday, Morsi’s opponents carried photos of Morsi with an X over his face and vowed that Friday would mark the beginning of his end in office. At a rival demonstration across the city, Morsi’s Brotherhood supporters swore that they would protect the elected president until their last breath.

“Legitimacy is from the ballot box!” they chanted. Of Morsi’s opponents, they yelled, “We will wipe the ground with them!”

All of Egypt seemed to be bracing for horrors that may come on Sunday evening, as demonstrations are expected to come to a head around the presidential palace and in Tahrir Square and other squares across the country on the first anniversary of Morsi taking office.

A military spokesman told the state news agency Friday that the military is deploying nationwide to avoid “a 28 January 2011 scenario,” referring to the deadliest day of Egypt’s popular uprising.

On Saturday, Morsi met with his defense minister and interior minister to discuss the security of vital institutions ahead of Sunday’s mass demonstrations, according to al-Masry al-Youm, an independent daily. The newspaper, quoting unnamed presidential aides, also said Morsi and his family had moved from their house — a residence separate from the palace — to a secondary presidential residence that would be easier to secure.

State media reported that gold shops had closed Friday in anticipation of unrest, and rumors circulated in wealthy and middle-class circles that ATMs would soon run out of cash.

The broad sense of impending doom marked a dramatic turnaround for this country of 85 million, where one year ago the first democratic presidential election in the country’s history brought Morsi to power and was deemed a step toward modernity and free politics after six decades of military dictatorship.

But many Egyptians, including some who voted for Morsi, are angry about how things have turned out. The president has failed to pull Egypt out of an economic quagmire or rectify its billions of dollars in debt. Morsi’s opponents say the president has focused instead on consolidating the power of the Brotherhood — actions that they say has deprived him of his legitimacy as head of state.

More than two years after revolution ended the 30-year rule of former president Hosni Mubarak, excitement about the democratic process has faded. Politics has created bitter societal rifts, fueling a standoff pitting a growing number of liberal, secular and poor Egyptians against the president’s Islamist supporters.

“Both parties think that they can win the game,” said Khalil al-Anani, an Egypt expert at Durham University in England. In recent weeks, members of opposition groups have portrayed the Brotherhood as “occupiers” of the state and extremist clerics have countered that the demonstrators are “infidels,” he said.

“They’ve adopted a very extreme discourse. And there is no common ground,” Anani said.

In his Saturday news conference, Obama noted that because Egypt is the largest country in the Arab world, continued instability could spread.

“We support peaceful protests and peaceful methods of bringing about change in Egypt. Every party needs to denounce violence,” he said. “We’d like to see the opposition and President Morsi engaged in a more productive dialogue about how to move the country forward. We do not take sides in terms of who should be elected by the Egyptian people, but we do takes sides in observing a process of democracy and rule of law.”

Opposition leaders are demanding the removal of Morsi and his prime minister. They also say they want the Islamist-dominated upper house of parliament dissolved and the constitution, which was drafted by an Islamist-majority committee but ratified in a national referendum, shelved and a new drafting committee and early presidential elections authorized.

For the pro-Morsi demonstrators who rallied outside a mosque near the presidential palace Friday, the protest served as a chance to defend the president against opponents who they say are trying to cheat the democratic process.

“He will not be removed except through the ballot box,” said Eid Mohamed, a factory technician from the Nile Delta.

Some wore orange hard hats and carried hard plastic tubing — “to defend ourselves,” said Said Osman, a factory manager who was also wearing protective glasses. Vendors hawked wrist and knee braces, as well as flashlights and laser pointers, on the assumption protesters would stay throughout the night. An ambulance waited on standby.

“Those who want to oust the president will have to walk over our dead bodies,” Osman said.

In Tahrir Square, opposition activists spoke with similar vitriol. Many blamed the United States for allegedly supporting Morsi, and they carried pictures of U.S. Ambassador Anne Patterson—also with an X over her face.

“I hope to remove Morsi and change the whole system,” said Haitham Amer, an insurance company employee who held a sign reading “Down, down, USA and Israel.”

The Republican Guard fortified security around Cairo’s presidential palace, but there was no security presence at Friday’s rival protests.

“Our faith in the police is about 30 percent,” said a Brotherhood spokesman, Gehad el-Haddad, who said the group had hired private security firms to protect its main headquarters.

He said he feared that without police or military to keep order, “you’ll find citizens on either side taking matters into their own hands.”

Martin Weil , Anne Gearan and Dana Hedgpeth in Washington, David Nakamura in Pretoria, South Africa, and Lara El Gibaly and Sharaf al-Hourani in Cairo contributed to this report.