One option lawmakers are considering to pay for new missile submarines to replace the current Ohio-class fleet is to create a separate fund for the program outside the Navy’s main shipbuilding budget.

The idea is to prevent the cost of building the vessels from swamping other Navy procurement objectives.

The Navy estimates that developing and acquiring a new strategic submarine starting around 2020 would devour one-third to half of its entire shipbuilding budget, and would force it to give up plans to acquire as many as 32 other vessels. Advocates of the separate fund argue the Navy should not have to shoulder the full cost of the new submarine because nuclear deterrence is a national mission, and is not limited to a single service.

The idea has strong support in both the House and the Senate. Language that would order the creation of a “National Sea-based Deterrence Fund” was approved in May by the Senate Armed Services Committee as part of the annual defense policy bill (S 2410). The House version of the defense bill (HR 4435) includes a similar requirement.

The Senate bill would authorize an initial $100 million in seed money for the fund, while the House version would authorize the Pentagon to move as much as $3.5 billion in unobligated fiscal 2014, 2015 and 2016 money into the new account.

Some outside analysts have derided plans to create a separate fund as “budgetary gymnastics” that would be fiscally unrealistic and irresponsible so long as overall defense spending limits remain in place.