Former US presidential candidate John McCain has called for some or all of the annual $1.5 billion (£1 billion) US aid package to Egypt to be withheld if a civilian government is not quickly restored in the country.
Most of the money goes to the military under an arrangement US leaders have honoured since Egypt's 1979 peace treaty with Israel.
The Republican Senator is among a group of Congressmen who believe the aid package should be adjusted because the latest military action in Egypt unseated a democratically elected president.
McCain said: "Regardless of what anyone thinks about Mohamed Morsi, he was elected by a majority of Egyptians last year.
"It is difficult for me to conclude that what happened was anything other than a coup in which the military played a decisive role.
"I do not want to suspend our critical assistance to Egypt, but I believe that is the right thing to do at this time".
The Muslim Brotherhood tells ITV News they are against violence but will "pay the price of their blood" to restore their ousted president.
Egypt's army has named two further officials in the transitional government as its supporters and opponents vowed to stay on the streets.
There has been outrage in Egypt after 51 people were killed near an barracks where ousted President Mohamed Morsi is thought to be held.