Bernie Sanders. Justin Sullivan/Getty Images Sen. Bernie Sanders of Vermont criticized President-elect Donald Trump's infrastructure plan Monday as "a scam" that benefits "billionaires" who "are already doing phenomenally well."

In a Medium post, the independent senator from Vermont and former Democratic presidential candidate roiled Trump's blueprint.

Sanders, along with many other Democrats, had expressed a willingness to work with Trump on infrastructure spending, a longtime priority of the party that many Republicans had eschewed in recent years.

"During the presidential campaign, Donald Trump correctly talked about rebuilding our country’s infrastructure," Sanders said. "But the plan he offered is a scam that gives massive tax breaks to large companies and billionaires on Wall Street who are already doing phenomenally well. Trump would allow corporations that have stashed their profits overseas to pay just a fraction of what the companies owe in federal taxes. And then he would allow the companies to “invest” in infrastructure projects in exchange for even more tax breaks."

It was Sanders' strongest rebuke of Trump's plan, which incentivizes companies to invest in infrastructure projects through tax breaks rather than direct spending. He has proposed an approximately $1 trillion plan to invest in rebuilding the nation's roads, bridges, and other infrastructure, though it has seen backlash from both sides of the aisle.

"Trump’s plan is corporate welfare coming and going," Sanders wrote.

Sanders contrasted the plan with his own, the Rebuild America Act, which he said he will reintroduce in Congress in January. The plan calls for $1 trillion in infrastructure investments over five years.

"Importantly, at a time when we need to reverse the 40-year decline of the American middle class, this legislation would create and maintain at least 13 million good-paying jobs, while making our country more productive, efficient and safe," he wrote. "Unlike Trump’s plan, which creates new tax loopholes and is a corporate giveaway, my Rebuild America Act would be paid for by eliminating tax loopholes that allow hugely profitable multinational corporations to stash their profits in offshore tax havens around the world."