"I'm not as phone-centric as they are", Gates said. She wants to impose a 6 per cent wealth tax on assets worth $1 billion or more, and is pitching a "Medicare for All" plan that would cost $20 trillion.
It comes after criticism of Ms Warren's policy from figures like Jamie Dimon, head of banking giant JP Morgan.
Democratic candidate and Senator, Elizabeth Warren has been a strong advocate of implementing a wealth tax. This would rise to 3% for any households with a net worth of over $1bn.
Gates was quickly proven wrong: Warren called out to Gates in a tweet and said she would "love to explain" exactly how much he would pay under a potential Warren presidency. Gates says Microsoft "screwed that up". "I do think if you tax too much, you do risk the capital formation" and innovation, as well as imperiling the U.S.
"I hope the more professional candidate is an electable candidate", he added. "You know, I'm not sure how open-minded she is", the billionaire philanthropist continued.
Unfortunately, Gates worries that an Epstein-like situation could happen again and that he could "credentialize" other billionaires through the Giving Pledge, which is Gates's and Warren Buffett's effort to convince the world's billionaires to commit to giving half of their money away to charity.
Gates added that he doubted that Warren - among the frontrunners for the Democratic presidential nomination - would be willing to meet with him after her recent comments about billionaires, including Leon Cooperman, the founder of Omega Advisors, who recently clashed with her. The debate has been partially spurred by tax reform under Donald Trump's administration, which the president dubbed "the biggest tax cut in history".
Mr. Trump said that tax cuts would help promote economic growth, but critics believe that interest rate cuts are particularly beneficial to the wealthiest people in the United States. "I'm not gonna, you know, make political declarations", he said. It is recommended that this money be used to address climate change and economic inequality.
Signatories included investor George Soros and Facebook co-founder Chris Hughes.