WASHINGTON – Construction companies no longer fret over finding work. They increasingly worry about finding enough skilled workers.

"The industry's workforce challenge is primarily a craft-worker shortage," said Stephen Sandherr, the CEO of the Associated General Contractors of America, adding that skilled hourly workers represent "the bulk of construction workers."

The worker shortage, highlighted in the group's new survey of members, is all the more pronounced because of indications that demand will grow for roofers, plumbers, electricians, carpenters and concrete masons — the very positions in shortest supply.

The U.S. Labor Department projects that demand nationwide for all those categories, except for carpenters, will grow considerably faster over the next decade than the pace of overall job growth.

Presidential candidates Hillary Clinton and Donald Trump are promising infrastructure spending to boost employment, but where are those prospective workers who will build new bridges and highways?

"You can put in all the money in the world, but if there aren't enough people out there to build it, it can't get built," said Ron Brown, executive vice president of State Utility Contractors in Monroe, N.C., which installs water and sewer pipelines.

Labor Department data shows that demand for masonry workers is expected to grow by 15 percent from 2014 to 2024. That's more than twice the rate of projected overall 7 percent job growth in the same period, according to the Bureau of Labor Statistics.

Similarly, demand for electricians is projected to grow 14 percent over that 10-year period. Demand for roofers is expected to grow by 13 percent and for plumbers by 12 percent. Only demand for carpenters nearly matches the overall growth, projected to rise by 6 percent.

"These worker shortages are occurring at a time when many construction firms have a low opinion of the pipeline for recruiting and preparing new craft workers," the survey noted in a summary. "Three-quarters of construction firms that responded to this survey rated that pipeline as poor or fair, while only 14 percent said the craft-worker pipeline was good or excellent."

In the survey of 1,500 members, the association said companies were dealing with the shortage by increasing hours, pay and benefits.

Almost half of the companies surveyed — 48 percent — reported that they had increased base pay for craft workers because of shortages. Some 47 percent said they were increasing overtime hours.

One potential solution to the worker shortage is allowing in more skilled migrants or finding a way to legalize those who are already here.

One longer-term solution is more vocational training in high schools and community colleges, something manufacturers and contractors have been pushing for a decade. The nature of manual labor has changed. Perceptions haven't.

"The equipment we run is computerized," said Brown. "They think, 'I'll be digging a ditch with a shovel the rest of my life.' And it's nowhere near that."