Emanuel has floated borrowing as much as $10 billion in pension obligation bonds to infuse the retirement funds with more cash, with the hope being that investment returns on that money would outpace the interest rates tied to repaying the debt. Sources close to Emanuel said the mayor does not plan to borrow the money before leaving office, but set up the possibility for a successor to do so. Some financial experts have described the borrowing plan as risky, and it has drawn opposition and concerns from many of the 21 candidates running for mayor in the Feb. 26 election.