Unlike Case 002, which saw more than 6,000 victim complainants, cases 003 and 004 so far only have 318.
Among those problems is that of forced deportation, a US policy that sends non-legal immigrants back to their presumed home countries.
In their letter, SRP lawmakers said more than 29,000 people from four different provinces had signed a petition.
Tribunal spokesman Lars Olsen said the Pre-Trial Chamber was under no time limit to consider Cayley’s appeal.
U.S. involvement in Southeast Asia was the focus of a speech Campbell gave Tuesday at the Washington D.C.-based research group.
The petition drives comes as the UN’s special human rights envoy for Cambodia, Surya Subedi, arrives in Phnom Penh on Monday.
Khmer Rouge victims and tribunal monitors have expressed concern over the amount of participation allowed to so-called civil parties.
Subedi is also expected to speak directly with residents in the Beoung Kak lake dispute.
In recent years, China has expanded its own political, economic and military ties with Cambodia.
Tribunal observers fear the court is trying to dismiss those cases in the face of stringent government opposition.
In a statement Thursday, the judges, Siefried Blunk and You Bunleang, called that analysis “baseless” and “nonsensical.”
Clearance of the unexploded ordnance could take up to a year or more, demining officials said.