Environmental activist and author Bill McKibben appeared on Countdown last night after environmentalists were arrested for a 4th straight day outside the White House protesting the Canada-to-Texas oil pipeline.

Host Keith Olbermann asked McKibben if he thought the protest could have an impact on President Obama's final decision to side with either the environmentalists or the oil industry.

"I think we are changing the odds at the moment," McKibben said. "A week ago, he would have gone ahead. Think of the pressure coming from the most powerful profitable industry on the power. We've succeeded by organizing the largest civil disobedience protest in the environmental movement in decades in nationalizing this issue."

Mckibben continued to address the success of the protests.

"It's no longer just people along the pipeline route and native people who've really been carrying this fight for a couple of years. Now it's people from all 50 states who have come to get arrested, and the media coverage they have been drawing is producing things like that editorial in the Times."

The author of Earth and professor at Middlebury College then turned the focus back to Obama on deciding the issue's fate.

"It's going to be gut-check time for the President," he said. "He hasn't yet done heroic things on the environment. He's done some good things around the edges, but nothing transformative, and he's back down on some important fights."

"This time, he can't blame it on Congress, he doesn't need to ask (Sen.) Jim Inhofe's (R-OK) permission. He doesn't need any help from the Congress. He can turn down the permit himself."

WATCH: Video from Current TV, which aired on August 23, 2011.