American workers are showing greater confidence regarding their jobs, with growing optimism toward the prospects of receiving a salary increase, as well as improved healthcare and retirement benefits. These are among the findings of the May Harris Poll Jobs and Benefits Security Index, which provides a score that is measured monthly to track the changing sentiment of today's American workers.

The online survey showed of 1,192 American workers was conducted between May 20 and 22, 2013 by The Harris Poll. (See findings here.)

Respondents showed slight growth from April in the perceived likelihood that they'll get a raise from their employer in the next 3 months (from 29 percent in April to 32 percent in May), though this is still down slightly from the March level (34 percent).

However, this positive sentiment is counterbalanced by raised expectations of more work for the same pay and concern about being replaced by a lower-cost employee. These positive and negative shifts effectively cancel one another out, resulting in May's aggregated concerns holding steady in comparison to April (57 percent each) and remaining slightly up from March (56 percent).

Much like the U.S. Department of Labor's May jobs report, the Index similarly finds brighter outlooks on benefits and salary counterbalanced by rising fears of either being replaced or having to pick up additional work with no commensurate pay increase.

• 18 percent of U.S. workers—up from 15 percent in April—believe that they will be replaced by a lower-cost employee.
• Workers are also increasingly afraid that they will have to work more without getting more money (56 percent, up from 53 percent in April and 50 percenet in March).