US employees are more willing than ever to test their options, to the degree that companies may have to replace one-fourth of their staff by the end of the summer, according to Spherion Staffing’s 2017 Emerging Workforce Study.

The survey found 25% of workers plan to look for a new job sometime in the next three months and 35% plan to do so sometime in the next year.

“In the 20-year history of the Emerging Workforce Study, we’ve never seen employees have this much leverage to improve their situation and fulfill their demands for better salaries and working conditions,” said Spherion Division President Sandy Mazur. “This year’s study reinforces the need for employers to re-evaluate their retention strategies and take a closer look at the factors — both financial and non-financial — that influence their workers’ professional decisions. While not all businesses will have the flexibility to raise wages right away, our data indicates that there are a range of alternative measures that may prevent an employee exodus.”

Twenty percent of the survey participants cited compensation as the primary reason they plan to explore their professional options, more than any other employment factor. Likewise, 35% of workers believe that although they accepted a lower salary when they started their current role, they should be paid more today.

Nearly two-thirds of surveyed companies, 62%, said they recognize a need to pay higher wages to remain competitive, but simply cannot afford to do so at this time. A significant segment, 74%, also noted that their competitors are raising wages to attract top talent.

“Feeling undervalued” topped the list of non-financial reasons workers gave for their interest in exploring alternate job opportunities. Likewise, 23% of workers feel their employers put in less effort to retain them this year than last.

The survey also more than one-third of workers, 38%, worry about falling behind in acquiring new skills needed for the future, while 37% feel they cannot achieve a promotion with their current skills alone. Additionally, only 18% of workers would give their companies’ training and development programs an “A” grade, while 46% would instead offer a grade of “C” or lower. In particular, employees are concerned that the training programs their company offers are not relevant to their skill sets, and thus nothing more than a distraction from their job duties.

The annual study was conducted online between February and March 2017 by global market research organization Research Now. It included 733 human resource managers and 2,062 employed US adults.