WATCH: Elizabeth Warren explains why her ‘wealth tax’ is key to saving democracy in America
Sen. Elizabeth Warren on MSNBC (screengrab)

Sen. Elizabeth Warren (D-MA) explained her "wealth tax" on MSNBC's "The Last Word" with Lawrence O'Donnell on Monday.

Warren has announced an exploratory committee as she considers running for president in 2020.

"You seem to be coming in policy first, front loading this campaign with policy," O'Donnell noted. "The latest, trying to tax wealth, not just wealth, but the super wealthy -- wealth accumulation above $50 million."

"This has gotten more attention than any policy yet announced by anyone in this campaign, and a lot of it is some pretty heavy attacks on you," he noted.

"What is your case for this wealth tax, which is not a form of taxation the federal government has tried before?"

Warren said it was a "fundamental fairness question" and explained why she wanted to "level the playing field."

She also detailed why she believes her proposal is critical for democracy in America.