Keystone xL pipeline and its partners managed to collect more than 100,000 signatures in the first hour of a 24-hour petition drive against the U.S. Senate effort to approve the Keystone XL pipeline. Reuters

A coalition of more than 30 grassroots organizations launched a 24-hour movement on Monday in an effort to deliver 500,000 e-mail messages to the U.S. Senate in opposition to a Republican effort to force the approval of the controversial Keystone XL pipeline.

The event, organized by the environmental organization, was formed in response to a Republican-backed effort to add an amendment to a crucial transportation package that would mandate the construction of the Keystone XL pipeline. The move, reported by The Hill, would effectively undermine the Obama administration, which rejected a permit for pipeline developer TransCanada Corp. in January after congressional Republicans attempted to impose a deadline on the decision.

We're going to war at noon eastern today--non-violent war, but a powerful, unified fight against the heart of right-wing power, the fossil fuel industry. We're out to collect half a million emails in 24 hours telling the Senate: back up the president and keep this pipeline dead, founder Bill McKibben wrote early Monday on the Web site Daily Kos.

As of 3 p.m. on Monday the effort, which is being supported by environmental heavyweights such as the Natural Resources Defense Council, the Sierra Club and the Environmental Defense Fund, surpassed 200,000 emails. reports the petition drive has received an enthusiastic following, surpassing the 100,000 mark only an hour after the campaign began.

The 1,700-mile Keystone XL would transport tar sands oil from Alberta, Canada to refineries in the Gulf Coast of the U.S. Although supporters of the project claim the pipeline would boost the nation's energy security and create much-needed jobs, critics argue the potential environmental impacts -- such as oil spills and increased output of greenhouse gas emissions -- would counteract any of the project's benefits. Moreover, several critics argue the job-creation numbers touted by TransCanada have been massively inflated.

Sens. Dick Lugar, R-Ind., John Hoeven, R-N.D., and David Vitter, R-La., are expected to file the Keystone amendment by Monday, according to The Hill. Last week, the Senate began debating on the massive transportation program funding bill, which would direct millions toward much-needed updates to U.S. roads, bridges and transit systems.

The source reports House Republicans also plan to attach a provision mandating the Keystone approval to their chamber's own version of the transportation and infrastructure package.