United States Senator Elizabeth Warren has expressed reservations about Stanley Fischer as vice chairman of the Federal Reserve, in an interview that aired on Bloomberg TV on Friday.

Speaking on the program “Political Capital with Al Hunt,” the Massachusetts Democrat and longtime consumer advocate said she expects incoming Federal Reserve Board Chairman Janet Yellen will be a more aggressive financial regulator than her predecessor, Ben S. Bernanke.

"I want to be hopeful," Warren said, when asked whether Fischer is a good choice for vice chairman.

"This is a hard time right now for the Federal Reserve," she said. "This economy has not recovered the way it should coming out of this recession. And what we’re seeing is the Federal Reserve has very limited tools. And in a world in which Congress is willing to act, a world in which Congress is not cutting back on spending using the sequester to cut back, shutting down the government, costing the economy $24 billion, Congress is supposed to do its part, the Fed does its part.

"Right now, the Fed just has very limited tools with monetary policy. And it keeps playing kind of the - working with the one tool that it’s got," Warren said.

Yet when Hunt pressed her, asking, "You like Yellen. I know that. But do you like Fischer?" she responded, "I want to - I want to be hopeful…that Fischer’s going to work in the right direction. I am not sure. "

In nominating Fischer, Obama on Friday said in a statement, "Stanley Fischer brings decades of leadership and expertise from various roles, including serving at the International Monetary Fund and the Bank of Israel."

"He is widely acknowledged as one of the world's leading and most experienced economic policy minds and I'm grateful he has agreed to take on this new role and I am confident that he and Janet Yellen will make a great team," Obama said.

Fischer served as Israel’s top banker for eight years, earning broad trust from citizens. He guided the country through the global financial crisis of 2008 and maintained relative stability during that time.