Bernie Sanders (I-VT), and senators Patty Murray (D-WA) and Ron Wyden (D-OR) sent a letter to Republican committee chairs with jurisdiction over Trumpcare requesting that they "schedule hearings to discuss, debate and hear testimony about the health care bill you are now drafting in secret".
Senate Republicans have held no committee meetings or votes on the measure.
The letter, which goes on to list each of the 31 rooms where a hearing could be held, says the millions of American who would be negatively impacted by Trumpcare "deserve an open and public debate over the bill".
The ad campaign comes as other organizations are ramping up opposition to the Senate GOP effort.
Meanwhile, The Hill reported that Senate Democrats are planning to bring the bring the work of the Senate to a halt by holding "a late-night talkathon Monday to protest the GOP's effort to repeal and replace ObamaCare".
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Democrats began tweeting under the hashtag "show us the bill" to protest the secrecy they perceive the Senate health care bill is being crafted beneath. But Democrats are attempting to draw attention to the behind-closed-door process that Republicans are taking in drafting the bill. Schumer said Democrats would not object to requests for unanimous consent on honorary resolutions, either. But they can make the process more painful by blocking routine Senate business, as Vox's Jeff Stein wrote recently.
U.S. President Donald Trump speaks about healthcare upon his arrival in Milwaukee, Wisconsin, U.S., June 13, 2017.
The House Freedom Caucus, which includes roughly 30 of the chamber's most conservative members, was among the first to support the effort.
McConnell, in a Senate floor speech, said Obamacare has increased costs and reduced choice, causing Americans to drop coverage.
There was also a $100 billion pool of money in the House bill to help states stabilize their insurance markets, which could be used to help people with pre-existing conditions. That was a significant part of the decision to spend $1.5 million, Community Catalyst Executive Director Robert Restuccia said. And the majority leader - the Senate majority leader, Mitch McConnell, makes the point that Congress has spent the last seven years learning about the Affordable Care Act and coming up with solutions.
"The Senate is working in secret and rushing to pass a bill", said Robert Restuccia, executive director of the group.