Electronic cigarette manufacturers are pushing hard for a policy rider in the year-end catchall spending bill that would shield them from a costly, time-consuming Food and Drug Administration approval process.

The FDA last year proposed the first-ever regulations for e-cigarettes, a growing market estimated by Wells Fargo Securities to be worth around $3.5 billion in 2015. Under the proposal, e-cigarettes that were on the market as of Feb. 15, 2007, are exempt or “grandfathered” from the agency’s review process. FDA officials stated they don’t have the authority to change that date, which was in the 2009 Tobacco Control Act.

But House appropriators included language in the fiscal 2016 spending bill that covers the FDA that would exempt any e-cigarettes on the market before the FDA regulations are finalized from the approval process required for new products. Final FDA regulations are currently undergoing review by the White House Office of Management and Budget, the last step before they are released.