According to a report released Tuesday by the Center for Climate and Energy Solutions (C2ES), formerly the Pew Center on Global Climate Change, the Obama administration has made “marked progress in its initial implementation” of a 75-point plan to tackle climate change without Congress, but it’s too early to gauge its ultimate success.

A year into the program and lacking support from a Republican-controlled Congress, Obama’s Climate Action Plan does not seek a new slice of federal revenue to fund its projects; instead, it asks federal agencies to reallocate resources from their existing and shrinking budgets.

“One of the main premises behind the climate action plan is it has required no new money and no congressional action, and that meant such a wide playing field for what the president could do,” Dan Weiss, director of climate strategy for the Center for American Progress, told Bloomberg BNA. “But that also means some important things can't happen without congressional action.”

Even after regulations like those recently proposed by the Environmental Protection Agency (EPA) to limit emissions from power plants are finalized, their success hinges on whether they survive in court and how congressional leaders may attack them, giving this year’s midterm elections an important role in climate policy.

Many Republicans are skeptical about whether global warming science is unbiased or if people are causing climate change. If they win control of the Senate in addition to the House, they could block elements of the Climate Action Plan and additional measures, including a $1 billion climate resilience fund Obama proposed in his fiscal 2015 budget in March.

To date, courts have largely upheld the EPA's authority under the Clean Air Act to regulate emissions. On Monday, U.S. Supreme Court justices reprimanded the EPA for seeking to expand its authority without congressional approval, but their decision allows the regulatory agency to limit emissions from the largest industrial facilities. 

“Much more work is left to do, and the White House will need to provide leadership," Eileen Claussen, president of C2ES, said in a statement. 

Since June 25, 2013, federal officials have rolled out policies intended to end U.S. aid to new overseas coal plants; cut emissions from coal mines operating on public lands; and add more solar, wind and other renewable energy generation on public land. The EPA has also proposed stricter rules to reduce emissions from trucks and, just three weeks ago, rules to cut emissions 30 percent by 2030 from 2005 levels at existing power plants.

Critics have pointed out that Obama’s plan doesn’t regulate emissions from petroleum refineries, oil and gas drilling on public lands, or airplanes.

According to the White House’s own report card, the bulk of the plan’s benefits won’t be realized until 2020 at the earliest.