WASHINGTON — Six Republican senators circulated a letter to their colleagues last week encouraging opposition to President Obama’s nomination of Ken Kopocis to lead EPA’s Office of Water, according to a press release.

The opposition is due to Kopocis' previous work on legislation to expand the scope of waters subject to federal Clean Water Act jurisdiction, noted the release.

The letter, signed by Sens. John Barrasso (R-Wyo.), David Vitter (R-La.), James Inhofe (R-Okla.), Mike Crapo (R-Idaho), Roger Wicker (R-Miss.) and Deb Fischer (R-Neb.), urges senators to vote against Kopocis on the Senate floor because as a congressional staffer he “was instrumental in failed efforts to remove the term ‘navigable’ from the CWA’s jurisdictional limitation to ‘navigable waters'," the release reported.

According to the release, the letter goes on to say Kopocis, who is currently a senior advisor in EPA’s water office, would “continue to advance and support EPA’s march towards an expanded federal encroachment of private property.”

The Senate Environment and Public Works Committee advanced the Kopocis nomination last month on a party-line vote, continued the release, and Democratic Senate leaders have not announced when the full chamber may consider it.

Read the full release here.