WASHINGTON — Silicon Valley once cheered the election of President Obama, comforted by his stance that Internet service providers should be banned from charging Web sites like Facebook or Netflix for faster access to American homes. And for much of the last six years, tech firms felt shielded from the possibility that the Internet would ever have slow and fast lanes for traffic.

But on Thursday, the government is poised to vote on a plan that could make that scenario a reality. Tom Wheeler, a Democratic Obama appointee, is pressing new rules at the Federal Communications Commission that would allow an Internet service provider such as Verizon to charge YouTube, for instance, for higher-quality streaming of videos.

The proposal has sparked an outcry of protest from Obama’s earliest supporters – consumer advocates, high-tech firms and investors, and Democratic lawmakers.

The FCC, which for years only heard from a handful of phone companies on its policymaking, has been flooded with more than 100,000 emails and calls to commissioners’ offices from consumers voicing concern about protecting the principle known as net neutrality, which says that all content should be treated equally online.

This week, a small group of demonstrators camped in tents outside the agency, calling for Wheeler to drop his “pay for play” rules. A question and answer session this week on Twitter with one of Wheeler’s top aides made FCCNetNeutrality one of the top terms on the site for the Washington region.

Silicon Valley is “very frustrated,” said Marvin Ammori, a technology policy consultant who helped organize a letter of protest to the FCC from more than 100 tech startups and big companies including Google, Facebook and Yahoo.

Ammori said the tech community picked Obama over Hillary Clinton in the 2008 primaries after he aggressively courted them, partly with his stance on the Internet. “They were the only really rich people in 2008 who weren’t already rich in 1996 and therefore not part of the Clinton family legacy,” said Ammori.

The FCC is an independent agency, as White House spokesperson Jay Carney pointed out when asked about Wheeler’s plan earlier this week. Carney added that Obama still supports net neutrality and “will be closely following developments as the FCC launches its proceeding.”

The plan is expected to get enough votes Thursday to move forward, with support likely coming from Wheeler’s two fellow Democrats on the commission. (The agency’s two Republican commissioners have opposed any attempt to regulate the Internet from the beginning.)

The next phase would be four months of public comments, after which the commissioners will vote again on redrafted rules that are meant to take into account public opinion. But the likelihood of final rules being enacted faces significant challenges.

The proposal has sparked a massive fight between two of the most powerful industries in this country: on one side, Silicon Valley, and on the other, companies like Verizon and AT&T that built the pipes delivering videos and websites to consumers’ homes.

Investors and executives from telecom firms and Silicon Valley have met with commissioners in recent weeks, picking apart the chairman’s plan.

The telecom firms say that without the ability to charge tech and media firms, they will not have enough money to invest in faster pipes for consumers.

Critics say the agency, under Wheeler’s predecessor and another Obama appointee Julius Genachowski, botched its earlier plan to institute net neutrality rules that would have reflected Obama’s views.

That attempt was struck down by a U.S. Appeals Court in January.

The FCC’s repeated stumbles and the stark retreat from Obama’s original goals reveals the thorny challenge of creating first-time regulations for the Internet – the very medium that has created rising populist campaigns in Washington.

Critics say rules crafted by Wheeler would be the first time the government explicitly permits Internet service providers to create online fast lanes for the highest corporate bidders. Startups would be at a distinct disadvantage over giants Facebook, Netflix, and Amazon who could afford to pay for better access to consumers.

Consumers could see higher costs for search, listening to music and updating social networks as companies such as Kayak, Spotify and Facebook try to recover expenses from doing business with Internet service providers.