U.S. Sen. Elizabeth Warren has called on the U.S. Fish and Wildlife Service to reject the request by the Tennessee Gas Pipeline Co. to extend a deadline for tree cutting along the path of its Connecticut Expansion Project pipeline in the southern Berkshires.

In a letter to the agency’s regional director, Wendi Weber, Warren said that Tennessee Gas Pipeline parent company Kinder Morgan has not secured rights to the entire pipeline route where it wants to begin tree cutting for the project. The company wants to extend tree cutting beyond the usual March 31 cutoff until May 1.

The company on March 7 asked the U.S. Fish and Wildlife Service’s New England Regional endangered species specialist to extend to May 1 the deadline for clearing trees, shrubs, saplings and associated vegetation along the project path. It also requested that the Federal Energy Regulatory Commission, which approved a certificate for the Connecticut Expansion Project on March 11, to allow it to begin cutting trees and other vegetation for the 13.42-mile-long looping expansion.

As part of the Migratory Bird Treaty Act, U.S. Fish and Wildlife limits tree-cutting to between Oct. 31 and March 31 to protect the habitat of several federally protected migratory birds and the northern long-eared bat — listed as threatened under the federal Endangered Species Act.

But a different letter, sent Tuesday to the company by Fish and Wildlife New England Field Office Supervisor Thomas R. Chapman, clarifies the time limits may not apply because the protected species may not be present. Instead, he writes that Tennessee Gas and the federal commission are to determine whether rules pertaining to the northern long-eared bat apply to the project, and the company needs to work to ensure that migratory birds in the project area are not adversely affected by clearing of vegetation.

Warren argued that the company “has not secured the rights to the entire proposed pipeline route,” particularly authority to take conservation land in Otis State Forest protected by Article 97 of the Massachusetts Constitution.

“I am troubled by Kinder Morgan’s attempts to circumvent federal and state requirements and demand hasty approval of tree-clearing and other potentially damaging activities,” she wrote.

The U.S. Fish and Wildlife Service deadline issue, along with the lack of the state Legislature’s approval of releasing state forest land protected under Article 97 and the lack of Section 401 water quality certification required under the U.S. Clean Water Act are among the issues being played out in two petitions this week for the federal commission to reconsider approval for the project, and in a Berkshire Superior Court lawsuit brought by the company. A hearing on the court case is scheduled for Friday in Pittsfield.

“The Connecticut Expansion Project has substantial implications for conservation efforts in Massachusetts, and it should not be rushed forward without full consideration of those impacts,” Warren wrote. “I urge you to reject the company’s request to extend the March 31 deadline for tree-clearing and to ensure that Kinder Morgan’s efforts do not come at the expense of critical environmental protections.”

Tennessee Gas Pipeline has said in its filings with the courts and with the federal commission that it needs to begin work to have the pipeline project ready for its customers by Nov. 1.

“Tennessee Gas needs immediate condemnation and entry to be able to commence construction by June 1, 2016 and complete construction by Nov. 1, 2016,” it wrote in its March 29 filing with the court. “Any delay jeopardizes Tennessee’s ability to meet these timelines, would result in increased construction costs by causing Tennessee to skip sequential construction and reply at a later date, and injures Tennessee’s customers — by preventing them from meeting supply forecasts provided to their customers and regulators.”