Elizabeth Warren invites billionaire critic to hearing on raising taxes on richest Americans

Senator Elizabeth Warren is inviting one of her more vocal critics to join her in the lion's den. The Massachusetts Democrat is asking former hedge fund manager and billionaire Leon Cooperman to air his views on her proposal to hike taxes on the nation's wealthiest at a hearing on Capitol Hill next week.

In a letter first obtained by CNBC and emailed by Warren's office to CBS MoneyWatch, Warren invited Cooperman to appear at an April 27 hearing on creating a fairer tax system, giving him until Thursday to respond.  Warren wrote that she specifically hoped to hear Cooperman's take on her ultra-millionaire tax that would have households worth $50 million to $1 billion pay 2% of their wealth in taxes annually, while billionaires would be taxed 3% on each dollar above that $1 billion threshold.