In Texas, 50% of the construction workforce is undocumented, says Cristina Tzintzun, executive director of the Austin-based Workers Defense Project (WDP), a workers' rights group focused on the building industry. Her office regularly deals with immigrant construction workers who are paid less than minimum wage, treated badly and face unsafe working conditions. "Construction is a dangerous industry, particularly in Texas, and when some workers do not have the same legal protection as others, some employers will take advantage of that," she says.

According to a January 2013 WDP report, 20% of Texas construction workers surveyed suffered a workplace injury that required medical attention, and 60% have never received basic safety training.

The report, titled "Build a Better Texas," also found that more than half of surveyed workers reported earning poverty-level wages, and 71% said they received no health or other benefits.

Sundt's Crawford says immigration reform will help to provide "a level playing field" among contractors and result in true competition. He says it also will help to ensure all workers are "treated with dignity" and given a safe workplace. "If we don't pass [a reform bill] this year, I don't know when we will," he says.