President Trump's tax plan is "really bad policy" that Democrats should oppose wholeheartedly, said Sen. Bernie Sanders, I-Vt., on Sunday.

"This is not a tax break for the rich? Well, I don't know what a tax break for the rich is," Sanders said on ABC's "This Week" with George Stephanopoulos.

"What this is is a massive transfer of wealth," he said, admonishing the release of the GOP tax reform plan earlier in the week.

Sanders wants more of the wealthiest in the country to pay a higher share of the tax burden. The working class "are the people who need help, ... not the top 1 percent," he said.

Sanders said the issue is not one of politics, while at the same time urging Democrats to stand firmly against the tax proposal.

"This is not politics. This is just really bad policy and I'm not clear why anybody would support a proposal which is massive amounts of tax breaks to the people who don't need it," he said.