Two years after Egyptians gathered for dramatic protests to bring down their leader, dissidents are bracing for deja vu.

The Tamarod -- "Rebellion" -- movement is planning massive protests Sunday calling for President Mohamed Morsy's impeachment. The group said nearly 20 million Egyptians had signed its petition by Wednesday.

"Since the arrival of (Morsy) to power, the average citizen still has the feeling that nothing has been achieved so far from the revolution goals which were life in dignity, freedom, social justice and national independence," the Tamarod campaign states. "(Morsy) was a total failure in achieving every single goal, no security has been reestablished and no social security realized."

The imminent unrest prompted the U.S. Embassy in Cairo to close its doors to the public on Sunday, which is normally a workday in Egypt.

"As potentially violent protest activity may occur before June 30th, U.S. citizens are advised to maintain a low profile and restrict movement to the immediate area of their residences and neighborhoods starting on June 28," the embassy said in a statement.

The Egyptian military said it would intervene if Morsy's Salafi supporters carry out their threats to disperse these protests by force. Salafis are hard-line Islamists who have called for Sharia law in the country.

Morsy came to power last year amid hopes that he could mitigate dissent stemming from two decades of ousted President Hosni Mubarak's rule.

CNN's Ian Lee contributed to this report.