U.S. Sen. Elizabeth Warren took aim this week at former Starbucks CEO Howard Schultz, arguing that his criticism of her plan to increase taxes on the super wealthy underscores the need for her proposal and others that seek to root money and influence out of Washington.

The Massachusetts Democrat, who is eying a 2020 White House run, hit back at Schultz for suggesting that her so-called “ultra-millionaire tax plan" is “ridiculous” and something that Congress will never pass.

Pointing to recent polls that found support for increased taxes on wealthy individuals, Warren argued that her plan to raise taxes on those making more than $50 million a year is not just popular, but something both Democrats and Republicans back.

The senator, however, offered that a possible barrier to her plan winning congressional support is billionaires like Schultz -- another possible 2020 contender -- who “pull the strings in Washington.”

“In Howard Schultz’s world, people like him who are rich and powerful get to block any popular policy ideas they don’t like. And if they feel so inclined, people like him can even buy themselves the presidency of the United States,” she said in a late-Tuesday fundraising email to supporters of her presidential exploratory committee. “Now, that’s ridiculous.”

Warren, who noted that she will not take money from corporate political action committees, Super PACs or special interests, urged supporters to join her grassroots movement “so we can make Washington work for working people, not just the billionaires who ran Starbucks.”

The senator further told Hill.TV Tuesday that while billionaires, like Schultz, "think that this government works just great the way it is,” it’s not working for anyone else.

Schultz, who is considering running for president as a third-party centrist candidate, criticized liberal policies like a “Medicare for all” health care system and tuition-free college in a Tuesday interview with NPR’s “Morning Edition.”

The former Starbucks CEO also slammed the senator’s proposal, which would impose a 2 percent wealth tax on those with at least $50 million in net worth and a 3 percent tax on those worth above $1 billion.

"When I see Elizabeth Warren come out with a ridiculous plan of taxing wealthy people a surtax of 2 percent because it makes a good headline or sends out a tweet when she knows for a fact that’s not something that’s ever gonna be passed, this is what’s wrong,” he said. “You can’t just attack these things in a punitive way by punishing people.”

According to Forbes, Schultz has an estimated $3 billion net worth.