If you want to get a sense of how impatient some of President Obama's most loyal supporters are getting when it comes to climate change, consider this: They're planning to conduct protests at meetings of the grassroots advocacy organization run by his former top campaign aides.

Environmentalists have become increasingly frustrated that Organizing for Action, the non-profit 501(c)(4) group that conducts issue advocacy on behalf of the president's agenda, isn't doing more to press for executive action on global warming. So these grassroots groups -- including CREDO Action, the political arm of the company CREDO Mobile, 350.org and others, intend to demonstrate at events OFA will conduct in the weeks ahead.

Climate change remains on the White House's agenda -- along with immigration and entitlement reform (and a few topics not of the president's choosing, such as his administration's handling of the Internal Revenue Service and Benghazi). And President Obama has made it clear he plans to use his executive authority to tackle global warming this term, but he has yet to unveil any specific measures on it so far this year.

Climate activists are particularly upset that OFA is not lobbying the president to reject the Keystone XL pipeline, a controversial project that would ship carbon-intense crude oil from Alberta to Gulf Coast refineries.

OFA, which has identified addressing global warming as one of its primary issues, has produced an Internet video mocking congressional Republicans for questioning the link between human activity and climate change, and has sent out multiple e-mails to members urging them to reach out to Congress on the issue. But it has not exhorted its activists to push the president to take action on the issue.

Now, with CREDO Action calling on its 3 million members to attend OFA meetings and push the president to reject Keystone -- whose environmental, economic and political impact is still under scrutiny by the State Department -- OFA has issued a climate change fact sheet specifically coaching people on the subject.

"Volunteers from Credo Action or other organizations may attend your planning session and want to demand that we work on the Keystone XL pipeline. Our mission is to change the conversation on climate and build support for action on climate change," the fact sheet reads. "We understand that there are groups and individuals who would like to work to influence the President and the State Department on a variety of environmental decisions, but OFA’s plan is to do great organizing on building clean energy locally, turning up the heat on Congress and helping individuals and communities switch to clean energy. They are more than welcome to work with those groups,but we encourage all volunteers to be part of our work and the mission of changing the conversation on climate!"

"Organizing for Action’s mission is to support President Obama’s agenda," the document continues. "The Keystone XL pipeline is still under review, and OFA supports and respects the process as it is currently underway."

In an e-mail, OFA spokeswoman Katie Hogan noted the group already mobilized its members to both engage lawmakers on global warming and press for confirmation of Environmental Protection Agency administrator-designate Gina McCarthy.

"It has been made clear since our first day as an organization that we support the President's plans from comprehensive immigration reform, to reducing gun violence to climate change, including the completion of the State Department review," Hogan wrote. "Just last week OFA held almost 100 action planning sessions on climate change in communities across the country to talk about the action that can be taken right now to call out members of Congress for denying that climate change is a man-made problem."

On Monday afternoon, for example, OFA launched a "Call Out the Climate Deniers" initiative, urging its supporters to "Click on your state to see the climate deniers that represent you."

These sort of statements are not enough to satisfy activists such as Daniel Kessler, a spokesman for 350.org, one of the groups opposed to the pipeline. While OFA does not currently occupy a headquarters at the moment, Kessler said environmentalists plan to show up at OFA town halls and other key events and make noise over the fact that the group cannot remain silent on the Keystone pipeline any longer.

"OFA leadership is going to have to choose if they want to listen to their membership or go their own way," Kessler wrote in an e-mail. "It's clear that Keystone will be a re-occuring problem for them if they don't take it on as a central issue to organize around. The president was elected to lead on climate, and the grassroots are saying that leadership starts with rejecting Keystone."

In an interview last week, Sierra Club executive director Michael Brune also expressed frustration with the administration's approach to global warming.

"We’ve yet to see a plan. There’s no shortage of ideas on what the administration could do, but no clarity on what the administration actually will do," Brune said. "Four months after the President’s inauguration, there’s no climate plan, no timeline, and an expansion of drilling on public lands. If this is what it means to make fighting climate a priority, then we’re all in trouble."

Obama may very well address environmentalists' concerns this year by rejecting TransCanada's application to build the Keystone across the U.S.-Canada border, and by regulating greenhouse gas emissions from existing power plants. But the longer he takes to act, the more likely his primary organizing group will face an organized rebellion of its own.