Ten U.S. senators are calling on Google to take “immediate action” to convert its growing number of contractors to full-time employees after six months of work.

The demand follows a New York Times report in May that said Google employed 121,000 contract employees and 102,000 full-time employees.

”Temporary workers and independent contractors are by definition intended for short-term and non-core work, and we urge Google to end any abuse of these worker classifications and treat all Google workers equally, ” the letter, which was addressed to Google CEO Sundar Pichai said. It asks for a response by Friday.

According to a Recode report in May, contractors made significantly less than full-time Google employees. Statistics from GlassDoor showed the median pay for contractors was $90,000 per year, while median pay for full-time employees was $128,000.

”The differences between the categories of workers appears to be in name only, ” the letter says. “In at least some cases, your company determines where these individuals work, the hours they work, the tasks they perform, and whether or not they should continue to work on Google contracts. In the case of temporary workers, they are commonly working on permanent projects alongside full-time Google employees for years and typically at much lower pay than their full-time employee counterparts.”

The letter says these are “abuses” of classifications for contractors and temp workers. It’s signed by Democratic Sens. Sherrod Brown, Patty Murray, Benjamin Cardin, Brian Schatz, Elizabeth Warren, Kamala Harris, Edward Markey, Richard Blumenthal, Richard Durbin and Bernie Sanders, who is an independent but caucuses with the Democrats.

“Google is valued at more than $100 billion, and your personal compensation topped $400 million in 2018, which makes it that much more difficult to stomach the mistreatment of these workers,” the letter to Pichai said. “It is not enough to insist that contracting and staffing companies pay at least $15 an hour and provide health care and paid parental leave because that standard is well below that set for Google’s full-time employees. Google should convert contractors and temporary workers to full-time employees.”

The letter from the senators asks for the following immediate changes:

Automatic transition from temporary worker to permanent full-time Google employee after six months;

Prohibition of financial disincentives — including “conversion fees” stipulated by staffing agencies in contracts with Google — for transitioning a temporary worker to permanent Google employee.

Wage and benefit parity for independent contractors, temporary workers and permanent full-time employees;

Disclosure to temporary workers at the start of their work on a Google contract about their status and when they can expect to transition to permanent full-time employee status;

Limitations on the use of independent contractors and temporary workers to temporary or non-core work that is not already performed by full-time employees;

Prohibition of mandatory nondisclosure agreements about the terms and conditions of employment, including in temporary workers’ contracts with their staffing agencies;

Elimination of all non-compete clauses in all employment contracts, including in temporary workers’ contracts with their staffing agencies; and

Google acceptance of liability for any workplace violations that occur with temporary workers or independent contractors.

Google disputes the arguments raised in the letter.

“We are proud to create economic opportunities for both the people we employ directly and our extended workforce of vendors, temporary staff and independent contractors, and believe that our practices in this regard accord with the highest industry standards. Respectfully, we strongly disagree with any suggestion that Google misuses independent contractors or temporary workers,” Eileen Naughton, VP of people operations, said in a letter to the senators.

“Independent contractors comprise 0.5% of our total workforce and we independently vet all of our independent contractors to ensure they meet the requirements of a 1099 workers,” Naughton said.

“Temporary workers comprise 3% of our total workforce, and do the job of a full-time Google employee but for a short period of time, working on temporary projects, addressing quick needs in business, incubating special projects, or covering for employees who may be on short-term leave, like parental or sick leave,” Naughton said.

Naughton added that Google opens up full-time roles for projects that require long-term support and that contractors can apply for those positions and will be considered along other qualified candidates.

“Being a temporary worker is not intended to be a path to employment at Google, and because we want to be clear and upfront, this is is a part of our written policies and the training that all Google employees managing temporary staff must take,” Naughton said.

Google will also require vendors who work in places like construction and food services at Google to pay a minimum of $15 per hour by 2022.

The House passed a bill in July to raise the minimum wage to $15 by 2025. The White House has said President Donald Trump will veto the bill. Some senators who signed the letter to Google, such as Warren, have also pushed to break up companies like Amazon, Google and Facebook.