President Obama in an interview released Saturday accused Republicans of exaggerating the job gains that would come with the construction of the Keystone XL pipeline, emboldening critics of the project as his administration weighs whether to give the project the green light.

“Republicans have said that this would be a big jobs generator. There is no evidence that that’s true,” he said in the interview published by the New York Times. “And my hope would be that any reporter who is looking at the facts would take the time to confirm that the most realistic estimates are this might create maybe 2,000 jobs during the construction of the pipeline — which might take a year or two — and then after that we’re talking about somewhere between 50 and 100 jobs in a economy of 150 million working people.”

If approved, the pipeline would carry oil from Canada to Gulf Coast refineries — the State Department is now reviewing the environmental impact of such construction. In a high-profile speech unveiling his plan to combat climate change, Obama last month said he would approve the pipeline only if he was convinced that it would not exacerbate greenhouse gases.

Obama, in this latest interview, stood by that pledge.

“I meant what I said. I’m going to evaluate this based on whether or not this is going to significantly contribute to carbon in our atmosphere. And there is no doubt that Canada at the source in those tar sands could potentially be doing more to mitigate carbon release,” Obama said.

At one point, Obama even suggested that the Keystone pipeline could lead to higher gas prices.

“Oil is going to be piped down to the Gulf to be sold on the world oil markets, so it does not bring down gas prices here in the United States,” he said. “In fact, it might actually cause some gas prices in the Midwest to go up where currently they can’t ship some of that oil to world markets.”

Keystone supporters have accused Obama of dragging his feet on the issue to placate green groups, noting that the original State Department analysis said the construction of the pipeline would not significantly increase carbon emissions.

Regardless of his decision, the president is likely to alienate at least part of his political base. Labor unions have welcomed what they consider a badly needed infusion of new jobs, while environmentalists say the climate ramifications of the project far outweigh minimal economic gains.

For his part, Obama seemed unconvinced by the arguments being made by labor interests.

“Well, look, [unions] might like to see 2,000 jobs initially,” he said. “But that is a blip relative to the need.”

Obama gave no indication of when he expects to give the final verdict on Keystone.