U.S. President Barack Obama’s goal to have more than 1 million plug-in electric cars on U.S. roadways by 2015 is well on its way to being completed, according to Assistant Energy Secretary David Sandalow.

Sandalow’s statement comes as delays of the Nissan Leaf and other concerns have fanned scrutiny of how the commercial viability of electric cars. Pike Research estimates that U.S. electric vehicle supply in 2015 will be closer to 841,000 cars. Sandalow made the statements at a meeting with the Society of Automotive Engineers in Detroit today.

The government released a report saying its the electric car supply in the U.S. will total 1.2 million cars by “conservative” estimates for 2015. The report doesn’t include key automakers like Toyota, which has the plug-in Prius planned for 2012, and startup Coda, which says it wants to sell an ambitious 14,000 of its electric sedans in its first year of production.

But the report projects supply of the Nissan Leaf in the U.S. this year to be 25,000 cars. By the DOE report’s account, 300,000 of the expected 1.2 million electric cars in 2015 will be Nissan Leafs, meaning the government expects Leafs to account for one in every four electric cars available by 2015. Nissan has to date only brought 453 leaf vehicles stateside. The company has about 20,000 reservations, and reportedly 40 percent of those reservations have become purchases. And Nissan seems to face a setback in the Leaf’s production every time it turns around — whether it’s a glitch in the system or a massive earthquake that stalls the car’s production line.

While General Motors seems to be faring better with production of the Chevy Volt — which will account for around half of the electric vehicles on the road, according to the report — the actual sales numbers this year for the Nissan Leaf will be anyone’s guess. But the Department of Energy seems confident enough — even though there isn’t any hard evidence that Nissan will be able to ramp up production to meet U.S. demand for the electric car.