The Constitutional Court may be approached for its say on the agreement for setting a couple of US bases on Bulgarian territory.
According to TRUD daily, Bulgarian magistrates are to rule whether the accord complies with the state's main law.
The agreement is expected for signature in April, along with a visit by US State Secretary Condoleeza Rice to Sofia.
The US has asked to be given access to a third military base in central Bulgaria, though negotiations have been so far focused on two sites alone.
An airfield at Graf Ignitievo, near the second largest Bulgarian city of Plovdiv, is said to match all of the Pentagon's requirements, defense officials have said.
According to TRUD as quoting experts, two bases in Bulgaria will deploy some 3,500 US militaries - a third one will possibly engage another 500.
About 2300 US servicemen are expected to go to Romania in 2006 as part of the same Pentagon restructuring plan.
Sofia and Washington have already reached an agreement on two other bases: one at Bezmer airfield and the other at Novo Selo shooting range.
The general command of the Bulgarian and Romanian troops will be in Romania.