Former Starbucks CEO Howard Schultz blasted Sen. Elizabeth Warren's (D., Mass.) proposed "wealth tax" as "ridiculous" and simply an effort to generate a positive headline for her campaign.

Schultz ripped into Warren during an interview on NPR's "Morning Edition" Monday and also mocked other left-wing policy proposals gaining a stronger foothold in the Democratic Party, like Medicare for all and and free college, Politico reported.

"Free Medicare for all, government-paid free college for all—first of all there’s no free. I mean, nothing is free," Schultz said

He is mulling running for president as a "centrist independent" to the great consternation of Democratic Party members, who fear he could siphon away votes from the Democratic nominee to the benefit of President Donald Trump.

Schultz, who has touted his opposition to the corporate tax cuts at the center of the Republican tax overhaul in 2017, called for "comprehensive tax reform" but didn't get specific when pressed by NPR's Steve Inskeep.

"We are in dire need of comprehensive tax reform," he said, "which would include a significant level of infrastructure development … I'm not trying to dodge any question. What we have today is an unfair system."

"However, 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 going to be passed, this is what's wrong," he added. "You can’t just attack these things in a punitive way by punishing people."

Warren didn't wait long to return fire, tweeting, "What's ‘ridiculous' is billionaires who think they can buy the presidency to keep the system rigged for themselves while opportunity slips away for everyone else. The top 0.1%, who'd pay my #UltraMillionaireTax, own about the same wealth as 90% of America. It's time for change."

What's "ridiculous" is billionaires who think they can buy the presidency to keep the system rigged for themselves while opportunity slips away for everyone else. The top 0.1%, who'd pay my #UltraMillionaireTax, own about the same wealth as 90% of America. It's time for change. https://t.co/D04G5fNvpa — Elizabeth Warren (@ewarren) January 29, 2019

Warren laid out her proposed "ultra-millionaire" tax last week, a flat tax of 2 percent on those with a net worth of $50 million or more. Those with $1 billion would be hit with a 3-percent tax. Her team says it would raise nearly $3 trillion over 10 years, but the Washington Post editorial board criticized it as difficult to implement and said it had an "authoritarian odor" by fining people who would renounce their citizenship to avoid the taxes.

Warren is running on a populist message of the system being rigged against the middle class, and she has earned a reputation as a scourge of Wall Street. Her campaign team compared her to Democratic icon Franklin D. Roosevelt in a fundraising email on Monday, due to a report of a bank CEO expressing fear over her becoming the 2020 nominee.

Schultz also criticized Rep. Alexandria Ocasio-Cortez (D., N.Y.) on Monday for her and her team's rhetoric against billionaires, saying such talk was "un-American." He referred to the young congresswoman as "misinformed."