One day after infuriating union leaders, Mayor Rahm Emanuel on Wednesday took his case for pension reform directly to rank-and-file members whose contributions he wants to raise and whose retirement benefits he's proposing to cut.

The mayor sent a letter to city employees to soften the blow of the bitter pill he's asking them to swallow: a 10-year freeze in cost-of-living increases for retirees; a five-year increase in the retirement age; a five-percent increase in employee contributions and a two-tiered pension system for new and old employees.

"If we follow along the current path, we will confront two stark choices: either the city's pension payments will squeeze its ability to offer the essential services that you provide or each of our pension funds will go bankrupt, leaving you and your families without retirement security," the mayor wrote.

"I do not want to underestimate the difficulty of these changes, but I do know that Chicago and our public employees will face far greater difficulties if we fail to take action. ... Not everyone will support what I have put forth, but I believe there are enough people who know that the moment of truth has arrived."