U.S. Sen. Ed Markey, D-Massachusetts, renewed his push for "net neutrality" protections Thursday, following reports that many major U.S. mobile carriers may be "throttling," or slowing down, certain services on their networks.

Markey, who led the U.S. Senate push to overturn the Federal Communications Commission's rollback of net neutrality rules, said the findings from researchers behind the app "Wehe" underscore the need for the Obama-era internet rules.

"Data collected through an app called Wehe shows that AT&T, Verizon, Sprint and T-Mobile all slowed down at least one video streaming service," he tweeted. "Given the opportunity, mobile carriers will discriminate against certain content and competitors. That's why we need net neutrality rules."

Data collected through an app called Wehe shows that AT&T, Verizon, Sprint and T-Mobile all slowed down at least one video streaming service. Given the opportunity, mobile carriers will discriminate against certain content and competitors. That’s why we need #NetNeutrality rules. — Ed Markey (@SenMarkey) November 15, 2018

Specifically, researchers found potential throttling on AT&T for YouTube, Netflix and NBC Sports; on Verizon for Amazon Prime, YouTube and Netflix; and on Sprint for YouTube, Netflix, Amazon Prime and Skype video calls, according to reports.

They further alleged "delayed throttling," or boosting, on T-Mobile for Netflix, NBC Sports and Amazon Prime.

In addition to pushing for net neutrality protections, Markey joined U.S. Sens. Richard Blumenthal, D-Connecticut, and Ron Wyden, D-Oregon, in pressing executives with AT&T, Verizon, Sprint and T-Mobile to detail whether they have implemented policies to "throttle" or prioritize internet traffic, if consumers can opt-out of such traffic differentiation and how the companies determine which network traffic receives faster or slower treatment.

Arguing that "all online traffic should be treated equally," the senators asked the companies to provide such information by Dec. 6.

The U.S. Senate, in a May vote forced by chamber Democrats, endorsed Markey's Congressional Review Act resolution to block implementation of the Federal Communications Commission-approved "Restoring Internet Freedom" order.

Markey turned to the CRA shortly after the FCC narrowly voted to repeal the 2015 net neutrality rules, which required companies providing broadband connections to act in the "public interest" and to not use "unjust" business practices -- preventing companies like Comcast, Verizon and AT&T from creating paid "fast lanes" and slowing or blocking web traffic.

They further classified the internet as a "telecommunications service" subject to Title II of the 1934 Communications Act -- not an "information service," and reportedly sought to address legal ambiguity caused by previous open internet regulations that had been struck down by courts.

The new FCC rules sought to restore the classification of broadband internet access service as an "information service," among other things.