Congressional Democrats embarked Tuesday on a wide-ranging campaign to probe Facebook, Google and their peers in the tech industry, a new burst of oversight that could bring heightened attention to some of Silicon Valley’s controversial business practices.

At the first major tech policy hearing since Democrats took control of the House, party lawmakers charged that long-standing inaction on Capitol Hill had left consumers unprotected in the digital age. They pledged to grill tech companies, shine a harsher light on their missteps and write tough federal laws, including new rules to protect web users’ online privacy.

“We’ve been talking about it for years, yet nothing has been done to address the problem,” Rep. Frank Pallone Jr. (D-N.J.), the chairman of the House Energy and Commerce Committee, said at the hearing. “It’s time that we move past the old model that protects the companies using our data and not the people.”

The early calls for new federal online-privacy protections represent only one facet of Democratic lawmakers’ wide-ranging tech agenda. Democrats have also promised to initiate probes to study social media sites, their approach to abusive content online, and the ways these companies affect competition and consumers.

Many House Democrats said the oversight awaiting Silicon Valley marks a dramatic shift from the chamber’s work under Republican control, which focused on allegations that social media platforms are biased against conservatives. Rep. David N. Cicilline (D-R.I.), who serves on a key House panel focused on competition issues, said last year was a “lost opportunity to look at [tech] in a serious way.”

“This is a really important moment for Congress to assert itself,” he said.

The tough talk from Democrats on Capitol Hill reflects the tech industry’s souring political fortunes since the Obama administration, when Silicon Valley avoided tough federal regulation. It faced its biggest challenge in Washington in response to revelations that Russian agents had used social media to help elect President Trump in 2016. Other lawmakers have grown impatient with tech companies, especially Facebook, for their privacy practices, and have called for investigations, fines and other penalties.

“The argument that these are immature industries, and need to be given free rein — I don’t think that applies there now among the most capital-intensive, successful businesses on the planet,” Rep. Adam B. Schiff (D-Calif.) said in a recent interview. “Vigorous oversight is now the new normal.”

Schiff, who became chairman of the House Intelligence Committee this year, said the panel plans to focus some of its work on social media sites. An early goal is to ensure Facebook, Google and Twitter aren’t weaponized by malicious actors during the 2020 presidential election, as Russian agents were able to do in 2016. Earlier this month, Schiff also created a special subcommittee focused on the threats posed by emerging technologies, including artificial intelligence, which could be used to create fake viral videos.

Other Democratic leaders also have pledged to scrutinize Silicon Valley’s expansive corporate footprint. On the House Judiciary Committee, a panel with jurisdiction over the legal issues facing the tech industry, lawmakers said they would hold hearings on whether companies including Amazon, Facebook and Google are too large, and if federal laws designed to protect competition are up to date.

"We've seen sort of a pattern, frankly, of [tech] making promises, deceiving the public and even trying to destroy competition,” Cicilline said.

And Pallone, who oversees the tech-focused House Energy and Commerce Committee, said in a recent interview that the committee plans to probe “concerns about hate speech and misinformation and algorithms.” The committee already has announced a hearing to study the tech industry’s lack of diversity.

The panel’s work began Tuesday with an inaugural hearing on online privacy. Rep. Jan Schakowsky (D-Ill.) opened the session by saying some tech giants’ data-collection practices “undoubtedly give Americans the creeps,” pointing to recent reports that apps pass sensitive information, including details about women’s menstrual cycles, along to Facebook.

“Without a comprehensive federal privacy law,” she said, “the burden has fallen completely on consumers to protect themselves, and this has to end.”

The frustrations with the tech industry span the Capitol: Rep. Greg Walden (R-Ore.), who chaired hearings with top tech executives on the Energy and Commerce Committee last year, also endorsed a federal law during the session Tuesday. In the Republican-controlled Senate, lawmakers plan to hold their own hearing focused on online privacy on Wednesday.

Adding to the pressure on Silicon Valley are new, tech-savvy Republicans who arrived this year in the Senate, including Sen. Josh Hawley (Mo.). The former Missouri attorney general has spent his first two months in the chamber sharply criticizing tech giants’ privacy practices and urging the Trump administration to take a closer look at the industry.

"I think it's time we take a very hard look at what these companies are doing in terms of data collection and disclosure,” Hawley said in a recent interview. “What I would consider progress by the end of the year is to see signs that the current legal arrangement is actually being enforced."

But lawmakers said the pressure is on the whole of Congress — not only newly galvanized House Democrats — to respond to the scandals of last year and set clear rules to keep Silicon Valley in line.

“I think, 2018, a lot of it was still basic education to members, to the public, and trying to have the companies at least acknowledge they have some responsibility from a public policy standpoint,” said Sen. Mark R. Warner (D-Va.), who has called for regulation to address troubles with social media.

In 2019, he added: “It’s time for us to put some proposals up.”