WASHINGTON – While the Defense Department says it needs to override federal environmental laws to properly train servicemen to protect themselves, Maine’s two Republican senators this week battled to stand up for the animals and plants that might have gotten trampled or blown to smithereens in the process.

“It’s not easy to achieve when you’re trying to address national security issues,” said Sen. Olympia J. Snowe in an interview on Thursday. “You have to decide how far you must go in either direction and reconcile those things as best you can.”

Snowe said it is possible to strike a balance. National security and the environment don’t have to be mutually exclusive, she said.

The position taken by Snowe and Sen. Susan M. Collins was a dangerous – and somewhat lonely – one, as it went against most of their party colleagues and it bucked the desires of Defense Secretary Donald H. Rumsfeld and Gen. Richard B. Myers, the chairman of the Joint Chiefs of Staff.

At one point, Collins and Snowe were two of only four Republicans voting for the stronger pro-environmental language, along with Sen. Arlen Specter of Pennsylvania and Lincoln Chafee of Rhode Island. Theirs were crucial votes in the 51-48 approval of the language in an amendment to the Defense Authorization Act that has been on the floor of the Senate much of the week.

“The Department of Defense should not be exempt from our environmental laws,” Collins said in a statement released after the vote.

Collins’ membership on the Armed Services Committee and Snowe’s role as chairwoman of the Senate Commerce subcommittee on Oceans, Fisheries and Coast Guard, positioned them to successfully push for the stricter environmental wording early in the process.

The amendment by Sen. Frank R. Lautenberg, D-N.J., that passed on Wednesday, requires the military to “effectively conserve the threatened species and endangered species” on land where it performs training exercises. Going beyond the original version of the authorization bill, the amended measure requires the Defense Department to include “assurances that adequate funding” will be provided to implement a land management plan to protect endangered species. Without the help of the Maine pair, the issue would have gone down in defeat, despite near unity among the Democrats.

“The Defense Department should follow the same environmental laws as everyone else,” said amendment sponsor Lautenberg.

During discussions on how to draft the bill in the Armed Services Committee, Collins fought an effort by the Pentagon to exempt the military from having to fully comply with four other major environmental laws – the Clean Air Act, Resource Conservation and Recovery Act, the Marine Mammal Protection Act, and Superfund, which aids in the cleanup of hazardous materials, according to Collins’ spokeswoman Megan Sowards.

Collins had told Sen. John Warner, R-Va., chairman of the committee, that if these anti-environment elements were in the bill, she couldn’t vote for it, and with the balance of power so tight between the parties, even the loss of that single vote could spell the kiss of death.

“Early on, she said that was something she couldn’t support,” Warner acknowledged on Friday. “In the end, she was very strong in expressing her concerns about the environmental aspects of this legislation.”

Warner said the offending provisions were part of a Pentagon request that was whittled down to exemptions for the Endangered Species Act and Marine Mammal Protection Act before the bill was even put together. Then, he said, the committee removed the protections in the Marine Mammal Act during the mark-up process in committee.

Environmental groups have characterized a similar provision in the House version of the defense authorization bill – which includes the Marine Mammal Act along with the Endangered Species Act – as an effort to “exempt” the military from honoring the same environmental laws that private companies and individuals must follow.

To bolster their case, the Pentagon trotted up powerful witnesses with resonating testimony.

Gen. John M. Keane, vice chief of the Army, told the Armed Services subcommittee on Readiness and Management in March, “Designations of critical habitat on Army installations adds management costs and reduces the availability of land on which to train.”

And Marine Gen. William Nyland, assistant commandant of the Marine Corp, told the subcommittee that endangered species and their habitat “significantly constrain” individual Marines and Marine units from digging fighting positions, gun emplacements and moving heavy equipment around a field.

But the Maine senators – both having taken prominent roles in working with the military in the past – were not swayed. Collins and Snowe, who had previously held the seat on the Armed Services Committee, said the Lautenberg amendment’s stronger language would not compromise the military’s ability to perform its training exercises.

To bolster her case, Snowe cited a report from the General Accounting Office indicating that environmental restrictions spelled out by the Endangered Species Act, have not impeded the military.

With the groundwork laid by Collins’ actions in committee, and with the two senators lobbying behind the scenes, that only left the Endangered Species Act provision for floor debate. Rather than take it on directly, however, supporters rallied behind a provision advocated by Lautenberg.

Under Lautenberg’s provision, the Interior Secretary would have to determine in writing that a plan – called the Integrated Natural Resource Management Plan – strikes an appropriate balance between military training requirements and the protection of endangered and threatened species.

That part of the bill essentially writes into law the management plan system, a procedure introduced during the Clinton administration through regulations to create a method by which the military can address habitat issues. The management plan is meant to supplement current rules that allow the Defense Department to request from the White House full exemptions from environmental restrictions.

The Defense Department has never sought a White House exemption, and it appeared that the thinking by the proponents of the bill – in ordering an Interior Secretary assessment – would make it even more unlikely.