U.S. Senator John McCain says Egypt has assured him it is working “diligently” to resolve a dispute with Washington about American pro-democracy activists facing Egyptian prosecution for working illegally in the country.

McCain said Monday he received the assurance as he led a delegation of five U.S. senators in talks with Egyptian military ruler Field Marshall Hussein Tantawi in Cairo. McCain expressed “guarded optimism” that the criminal charges filed against the U.S. non-governmental organizations will be resolved “fairly soon.”

Egyptian authorities plan to open a trial on Sunday for 43 pro-democracy activists accused of working in Egypt and accepting foreign funds without a permit. The activists include 19 Americans, among them Sam LaHood, a son of U.S. Transportation Secretary Ray LaHood. Some U.S. officials and lawmakers have warned Egypt that it risks losing its $1.3 billion in annual U.S. military aid if it goes ahead with the trial.

McCain said making threats against Egypt is counterproductive. He said his delegation's meetings with Egyptian officials were aimed at finding a mutuality of interest and supporting what he called the country's “very difficult transition to democracy” from military rule.

Another member of the U.S delegation, Senator Lindsey Graham, criticized the Egyptian case against the pro-democracy activists as “politically motivated” and blamed it on an individual with an unhelpful agenda. His comment was an apparent reference to Egyptian Minister of International Cooperation Faiza Abul Naga, a prominent critic of the NGOs and an aide of ousted President Hosni Mubarak.

The U.S. delegation also met with Egyptian lawmakers and members of the Muslim Brotherhood, the main Egyptian Islamist group whose political party won the most seats in a phased parliamentary election that ended last month. The senators said Brotherhood representatives promised to revise the restrictive NGO law under which the American activists have been charged.