The top Republican on a key senate committee warned Tuesday that US assistance to Egypt could evaporate if American pro-democracy activists there are jailed.
Cairo is believed to have plans to put dozens of activists, including 19 Americans, on trial, and their cases have caused a rift in US-Egypt relations.
"If anybody goes to jail I think there'll be a backlash you can't contain," Senator Lindsey Graham told reporters.
Asked if that meant scrapping the $1.3 bn (Dh4.7bn) in aid that Washington provides its Arab ally, Graham replied "Yes, I think very much at risk."
"The red line for me is incarceration. If any American or NGO (non-governmental organization) staff member is pre-trial confined or post-trial confined, that's just an absolute overreaction," he added.
"If they don't really embrace international organizations that are providing assistance to the Egyptian people to help form a new democracy, that's going to be very difficult for the Congress to ignore."
The offices of several local and international NGOs including Freedom House and the International Republican Institute were raided in December by Egyptian authorities as part of a probe into alleged illegal funding.
Then last month, Egypt barred some US members of the NGOs from leaving the country, including Sam LaHood, the son of Transportation Secretary Ray LaHood.
American officials said "a handful" of the pro-democracy activists subsequently took refuge inside the US embassy, fearing arrest.
Graham said he believed ordinary Americans and Egyptians had a "meeting of the minds" in terms of wanting to halt the aid.
"Seventy-four percent of the people in Egypt say they don't really want our money. I bet you 74 percent of Americans say we don't want to give it to you either."
Other US lawmakers have begun to openly question US-Egypt ties as a result of threatened legal action against dozens of people, including Egyptians.
Democratic Senator Ben Cardin, a member of the Senate Foreign Relations Committee, said Monday that Washington should "re-evaluate" the bilateral relationship, adding that it was "totally unacceptable" for Egypt to prosecute the activists on charges of illegal funding of aid groups.
The United States on Sunday demanded "clarification" from Egypt over its apparent plans, which threatened to further strain Washington's ties with Cairo's post-Arab Spring military rulers.