WASHINGTON (AP) – Democrats on Wednesday launched what will be an uphill battle to require that companies give their workers seven paid sick days a year, saying it will make employees more productive and prevent them from spreading illnesses in the workplace and the schools.

Sen. Edward M. Kennedy, D-Mass., and Rep. Rosa DeLauro, D-Conn., said their legislation will affect companies with 15 or more employees, and would extend the benefit to more than 46 million workers who currently have no paid sick leave.

Kennedy acknowledged it will be a tough fight, but said he hopes it won’t take as long as it took Congress to pass the Family and Medical Leave Act, which gives workers the right to take unpaid leave for extended illness or to care for a sick child or family member. That took more than seven years.

He said he is talking to Sen. Mike Enzi, R-Wyo., who is chairman of the Senate Health, Education, Labor and Pensions Committee, about gathering support and scheduling a hearing on the legislation. Kennedy is the ranking Democrat on the panel.

“Taking time off to treat illness and injuries will save health costs in the long run,” said Kennedy, noting that when his son was diagnosed with cancer he was able to take time off to be with him. “But year after year countless employees have to choose between the job they need and the family they love.”

DeLauro said paid sick leave is common sense. Too often, she said, parents send their sick children to school because they can’t take a day off work to care for the child. And that, she said, spreads illnesses and reduces productivity.

A study by the Institute for Women’s Policy Research determined the total cost of the bill to businesses would be about $20 billion – or about $6 per employee per week. But the study said businesses will also save money in reduced employee turnover and greater productivity.