Just days after President Trump dealt a final blow to Obama-era internet privacy rules, Senate Democrats are trying to bring them back to life.

Sen. Ed Markey introduced legislation Thursday that would prohibit Internet service providers like Charter and Comcast from selling personal information about their customers, like web browsing history and app usage data, without first getting their permission. Backed by 10 of his Democratic colleagues — including Senators Elizabeth Warren, Bernie Sanders, and Al Franken — the bill would re-establish landmark privacy rules passed in the final months of the Obama administration.

But Sen. Markey and his co-sponsors face a determined Republican majority that fiercely opposes such rules and just voted to overturn them.

Last week, the House of Representatives moved to repeal the ISP privacy rules largely along party lines, in a 215–205 vote. And in March, all 50 votes in favor of stripping the rules were cast by Republicans.

Despite the recent loss in Congress, Democratic lawmakers and consumer advocates believe that the fight over internet privacy has mobilized voters, highlighting previously obscured privacy practices that nonetheless affect every American who uses the internet.

The new proposal, like the internet privacy rules passed by the Federal Communications Commission last year, would make it harder for ISPs to collect and sell the information of its customers. A key provision would designate web browsing history as "sensitive" information, meaning that internet providers would first need to get your permission before they could share or sell that data.

The Obama-era FCC rules were scheduled to take effect later this year. But with the Congressional repeal and Trump's signature, the rules were scrapped and never kicked in. Now, your ISP can do some pretty invasive things with your private data.

“Thanks to Congressional Republicans, corporations, not consumers, are in control of sensitive information about Americans’ health, finances, and children," Sen. Markey said in a statement to BuzzFeed News. “This legislation will put the rules back on the books to protect consumers from abusive invasions of their privacy. Americans should not have to forgo their fundamental right to privacy just because their homes and phones are connected to the internet.”

For their part, Senate Republicans saw the privacy rules as onerous regulations that unfairly targeted ISPs. Other internet companies, like Facebook and Google, for instance, didn't have the same restrictions placed on them limiting what they could do with customer data. Sen. Jeff Flake, who led the Senate's efforts to repeal the rules, has argued for a more "light touch" approach from the government. "What we need with the internet is uniform rules, and not to regulate part of the internet one way and another part of the internet another way," he said after the Senate vote in March.

Shortly after Congress voted, Comcast, Verizon, and AT&T each defended their commitments to privacy, and claimed in posts on their corporate websites that little would change following the repeal of the ISP privacy rules. But policy experts and privacy advocates were quick to reject their assurances.

On Wednesday, Sen. Markey sent letters to AT&T, Comcast, Charter, Verizon, Sprint, T-Mobile, and CenturyLink asking them share details on their data collection and privacy practices. Among the 16 questions listed, Sen. Markey asked whether they get consent before collecting their customer browsing history and if they had changed their privacy policies since Trump signed the repeal. Sen. Markey asked that they respond by May 1.