The clock is running down on the final day of the largest national call-in campaign ever organized by climate and environmental groups. In the first 48 hours of this historic “72 Hours for Clean American Power” event, 200,000 Americans phoned their senators to demand a comprehensive, aggressive clean energy and climate change bill that fuels job growth, reduces emissions, and safeguards our future.

Earthjustice is among nearly 50 groups teamed up for this mass effort—and the impact is clear. Senate phone lines have been ringing off the hook with the message that America wants clean energy, America wants the certainty of future jobs, and America wants an economy that will lead the rest of the world into the 21st century.

Voters are at this very moment speaking out for clean air, clean water, preserved wilderness, and a safer land for future generations. They want the Senate to get to work on crafting and passing bill that ensures all this.

Senators are also hearing from U.S. war veterans demanding a secure future independent of foreign oil and thorny geopolitics. This morning, the veterans group VoteVets.org debuted a provocative advertisement that pushes for clean-energy legislation as a national security imperative.

Until the Senate passes such a bill, there is only one other recourse. As determined by the Clean Air Act and the Supreme Court, the EPA has the authority and responsibility to regulate air pollution and greenhouse gases. The EPA began the process last December and since then, some senators, led by Lisa Murkowski of Alaska, and as of today, John R. Rockefeller of West Virginia, have attempted to blockade the EPA’s authority and cut down the Clean Air Act.

Meanwhile, the list of senators, states, mayors, state agency leaders, associations, and legions of groups nationwide who are defending the EPA’s action on regulating greenhouse gases and combating climate change continues to grow.

On Monday (March 1), the U.S. Conference of Mayors, comprising 1,000 mayors from across the country, wrote to the Senate in defense of the EPA’s action and against these efforts to blockage progress on the issue:

Instead of embracing the progress of state and local governments to combat climate change, efforts to block all or part of the Clean Air Act would seriously undermine the overwhelming science of climate change and further exacerbate impacts to national security and public health and welfare. Additionally, these efforts hold back billions of dollars in job-creating clean energy investments all across the country.

Yesterday (March 3), more than 25 agricultural and rural-community organizations sent a letter to the Senate, speaking out on behalf of farmers and communities:

Agriculture is uniquely vulnerable to the effects of climate change. From persistent droughts in the South to increased flooding in the Midwest, farmers are already experiencing the effects of a changing climate. To produce healthy, abundant and safe food crops, farmers need not only clean air and water, but also protection from the increased risk of droughts, floods and temperature extremes that climate change is already threatening. Failure to act on climate change therefore puts at risk not only farmers’ livelihoods, but also the security of our nation’s food supply.

Support for Senator Murkowski’s resolution to block EPA regulation of greenhouse gases would be a vote against the health and security of our nation’s farms and of the livelihoods of our farmers. Fears that farmers and ranchers would be unduly burdened by these regulations appear to be not only short-sighted, but incorrect.

To get your senator’s phone number, visit the Earthjustice 72 Hours for Clean American Power action site. Let’s spread the word and use these last few hours of this national call-in event to send a strong message to the Senate!