In this Feb. 13, 2014 file photo, members of the Box Elder County Sheriff's Office fly their search and rescue drone during a demonstration, in Brigham City, Utah. (AP Photo/Rick Bowmer, File)

Senate lawmakers are pressuring the Federal Aviation Administration to speed up its efforts to develop rules for drones — and at least one senator is objecting to a restrictive proposal that could put commercial drones out of reach of all but the wealthiest companies.

In a letter to FAA administrator Michael Huerta, a group of lawmakers led by Sen. Ron Wyden (D-Ore.) are demanding that the FAA speed up its deliberations for integrating drones into the national airspace. The agency was supposed to come up with draft rules governing small unmanned aerial systems this August, but it missed the deadline — and it's not clear how much longer we'll have to wait.

"These delays force manufacturers and operators who play by the rules to sit on the sidelines while they wait for approval," Wyden wrote along with Sens. Jeff Merkley (D-Ore.), Heidi Heitkamp (D-N.D.), John Hoeven (R-N.D.) and Cory Booker (D-N.J.), "while others chance fines and operate without any certification from the FAA, which raises serious concerns about public safety."

The FAA recently began allowing some companies use drones for commercial purposes in special circumstances. But the application process takes far too long, the senators said in the letter.

A version of the FAA's proposed drone rules reported by the Wall Street Journal Sunday would force drone pilots to show a pilot's license and hours of experience flying manned vehicles before they would be allowed to touch the controls of an unmanned craft. Other provisions would allow commercial drones to be flown only during the day and below a ceiling of 400 feet. The rules would apply to all drones under 55 pounds, without distinguishing between larger commercial systems and smaller, lighter craft common among hobbyists.

Industry groups immediately criticized the plan as unworkable. Now it seems that a growing number of lawmakers agree.

"In light of recent reports, I am concerned that proposed regulations on small, commercial unmanned aircraft will be costly, needlessly restrictive and hinder research and development for the growing [unmanned aerial systems] industry," said Wyden in a statement. "The FAA needs to act quickly to alleviate these concerns."

On Sunday, Sen. Charles Schumer (D-N.Y.) called on federal regulators to speed up their rulemaking process after drones nearly collided with manned aircraft several times at John F. Kennedy International Airport over the weekend.

Given that it took half a decade for the FAA to come up with such sweeping and conservative rules, however, chances are it will be a while before the agency comes up with anything more nuanced.