AUGUSTA — Sen. Susan Collins’ effort to relax some rest rules for truck drivers is drawing fierce criticism from safety advocates, but Maine’s Republican senator says the current regulations have had unintended consequences.

Currently, drivers are limited to 60 hours on the road in seven days or 70 hours over eight days. A driver can take a 34-hour break to restart the clock on their work week, but it has had to include at least two consecutive overnight rest periods between 1 and 5 a.m.

Her measure would remove the mandate on overnight rest periods, allowing truckers to begin their new work week at night instead of having to wait until the next morning.

Collins wants to suspend the existing regulations for about a year while the federal government studies their efficacy. Her proposal is an amendment included with a 1,600-page, $1.1 trillion spending bill being considered by Congress.

She stressed that all other rules would remain in place, including the requirement that drivers can be behind the wheel for only 11 hours per day.

“There is increasing concern that these regulations are forcing more trucks on the road during the most congested morning hours – during a time when commuters are traveling to work and children are traveling to school,” Collins said in a statement.

But critics say the change could lead to more accidents by encouraging drivers to spend longer hours on the roads.

Department of Transportation Secretary Anthony Foxx said in a letter to lawmakers this month that the change would increase the time drivers could be on the road per week from 70 hours to more than 82 and lead to more accidents.

Daphne Izer, founder of Parents Against Tired Truckers, said the changes would result in even more “death and destruction on our highways.” The rules affect only about 15 percent of truckers — the long-haul drivers, she said.

“It’s all about corporate greed. There’s good companies out there. But the ones that are not will push the drivers,” said Izer, whose teenage son and three of his friends were killed in October 1993. A trucker fell asleep and ran over the teens’ car, which was parked in the breakdown lane of the Maine Turnpike.

Supporters counter that it’s unlikely drivers would reach that limit.

“Their argument in our mind is disingenuous,” said Brian Parke, president of the Maine Motor Transport Association. “It’s predicated on something that’s unlikely, improbable and relies on imaginary logistics. Mathematically it could be possible but practically, it’s not likely.”

Lawmakers in Washington were moving toward passing the larger spending bill before a midnight deadline.