A controversial proposal by the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers to expand the definition of wetlands under federal protection has already drawn more than 200,000 comments. Among the commenters: hundreds of members of Congress, most of them Republican, criticizing the initiative, according to analysis by Docket Wrench.

At issue is a proposal to resolve the definition of regulated wetlands following a pair of Supreme Court decisions, in 2001 and 2006, that left the situation murky. It would revise regulations that have been in place for more than a quarter of a century.

This May letter signed by signed by 231 House members, including five committee chairman, decries the proposal, “Although your agencies have maintained that the rule is narrow and clarifies [Clean Water Act] jurisdiction, it in fact aggressively expands federal authority under the [Clean Water Act] while bypassing Congress and creating unnecessary ambiguity. Moreover, the rule is based on incomplete scientific and economic analyses.” Nineteen of the signers are Democrats.

Another letter from Sen. Pat Toomey, R-Pa., chairman of the Senate Republican Steering Committee, along with 14 fellow conservative senators, says “we believe that this proposal will negatively impact economic growth by adding an additional layer of red tape to countless activities that are already sufficiently regulated by state and local governments.”

Arizona Republican Sens. John McCain and Jeff Flake weigh in with a missive charging that the proposal does not take into account water conditions in arid states and urges the agencies “to abandon the current proposed rule.”

Other lawmakers writing individually include Reps. Marcia Fudge, D-Ohio, David Loebsack, D-Iowa; and Doug Collins, R-Ga.

The EPA has logged nearly 205,000 comments on the proposal to date and recently extended the July deadline to October. However, the agency has posted the text of just 4,500 of those letters. This is because the agency has concentrated on posting unique comments as opposed to form letters, according to agency spokeswoman Julia Ortiz. This makes it difficult to determine whether the majority of letters are positive or negative.

However, among the letters posted, many appear inspired by the American Farm Bureau, a fierce opponent of proposal. The Farm Bureau is a powerful political force; in the 2012 election cycle, the group reported spending $12.6 million on federal lobbying and $2.6 million on campaign contributions. A long list of developers, agricultural interests, petroleum, mining, and indutry groups are opposed to the rule, including the Chamber of Commerce, the National Association of Homebuilders, and the National Association of Realtors.

Environmental groups strongly favor the expanded definition of wetlands. A cluster of letters comes from this alert by the group Earth Justice, with advocates writing, “I urge EPA to ensure that this proposed rulemaking accurately captures the important functions of streams, wetlands, and other important waterways, and finalize this important rulemaking quickly.”

This month, in both the House and Senate, lawmakers introduced legislation that would if approved stall the EPA’s efforts to expand the definition of wetlands. In the Senate, S. 2496 is sponsored by Sen. John Barrasso, R-Wyo., and has gathered 37 cosponsors. In the House, H.R. 5078 has 60 cosponsors.