The poll numbers for Senate Republican candidates take an approximately 30-point hit when voters learn they’re supporting their party’s bill to repeal and replace Obamacare, according to a poll set to be released on Friday.

The poll found that, in a vacuum, voters in 10 battleground states are split almost evenly about Republican senate candidates — with 21 percent of voters viewing them favorably and 20 percent viewing them unfavorably.

But when told their Republican senate candidates supported the GOP’s health care bill, voters turned sharply against their representatives. In that case, the candidates’ unfavorability rating jumps from 21 percent to 52 percent, according to the new polling from Priorities USA and Senate Majority PAC.

The numbers are even more dramatic when the polling is mixed in with attacks on the GOP health bill. “After hearing criticisms of the Republican plan, voters in these Senate battlegrounds went from leaning toward voting the Democrat in 2018 by a healthy 48-38 margin, to leaning toward the Democrat by an even more robust 56-35 margin — an 11-point jump,” the poll stated.

Now, it’s not particularly surprising that the health bill would prove a drag on Senate Republicans’ polling numbers. Both the House and Senate versions of Obamacare’s repeal bills have consistently polled below 20 percent, in addition to sparking dozens of protests across the country.

But the poll may prove encouraging nonetheless to Democrats looking at a 2018 Senate map so friendly to Republicans that many experts consider it largely out of reach. As Vox’s Andrew Prokop has explained, Democrats will be defending a massive 25 seats in 2018, compared with just eight for Republicans. Donald Trump won five of the states Democrats will have to defend; Hillary Clinton only won one of the seats Republicans are defending.

That said, nobody really knows just how much of a political vulnerability the GOP health bill will prove. The special elections have only proven a partially useful test case, given that none of the House Republican candidates who won actually had to cast a vote on its behalf. This new data suggests Democrats can hang the health bill around their neck — assuming, that is, that they support it.

You can read the report in full below or at this link. The Global Strategy Group and the Garin Hart Yang Research Group also helped produced it.