Nearly 150 Internet firms are banding together to call for more stringent net neutrality regulations on broadband providers.

In a letter to the Federal Communications Commission on Wednesday, the companies asked federal regulators to reconsider a proposal that critics fear would allow Internet providers to charge for faster, better access to consumers. The list includes Amazon, Facebook, Google and Microsoft, along with dozens of other firms that called the prospect of paid fast lanes "a threat to the Internet."

With just a week to go before the Federal Communications Commission meets to consider its proposed new rules for ISPs, the letter represents a late attempt by Silicon Valley to take a stance on the open Internet.

"Instead of permitting individualized bargaining and discrimination," the companies wrote, "the commission's rules should protect users and Internet companies on both fixed and mobile platforms against blocking, discrimination and paid prioritization, and should make the market for Internet services more transparent."

The companies have not gone so far as to demand the FCC "reclassify" Internet providers under Title II of the Communications Act — a move that would allow the commission to regulate ISPs more heavily, as it does with phone companies. The letter does not offer an alternative proposal.

Even as the companies were writing to the commission, however, some at the agency were suggesting that the May 15 meeting be delayed.

"I can tell you right now I have real concerns about process," said FCC Commissioner Jessica Rosenworcel in remarks at a Washington conference of state library officials. "Rushing headlong into a rulemaking next week fails to respect the public response to his proposal."

In a Google Hangout Wednesday, Rep. Anna Eshoo (D-Calif.), who represents the district in which many of the tech companies are based, said Rosenworcel was "on target" in requesting a delay.

"I really don't know how the FCC can absorb everything that's washed over the agency in just a handful of days without some kind of a delay," she said.

FCC Chairman Tom Wheeler indicated Wednesday that he still intends to address net neutrality next week.

"Moving forward will allow the American people to review and comment on the proposed plan without delay, and bring us one step closer to putting rules on the books to protect consumers and entrepreneurs online," said Wheeler spokeswoman Shannon Gilson.

Once the proposal has been publicly unveiled on May 15, the public will still have opportunities to comment on the idea.