(CNN) Less than 24 hours after they narrowly passed the American Health Care Act, 20 Republican House members are already feeling the negative political effects of that vote.

The Cook Political Report, a non-partisan campaign handicapping service (and my first employer in Washington!), changed the ratings on 20 GOP-held districts Friday morning -- all of them moving in Democrats' favor in advance of the 2018 midterm election.

A look at the 20 Republican seats that got more vulnerable after the AHCA vote

"For several dozen Republicans, adding support for the AHCA to their voting record is an unequivocal political risk. And, several of the 20 Republicans who voted against AHCA could end up being blamed anyway, much as 17 of the 30 Democrats who took a pass on the ACA and then ran for reelection ended up losing in 2010. For others, tough votes could make the prospect of retirement more appealing."

The majority of the 20 members made more vulnerable in this latest round of Cook Report ratings represent districts that Hillary Clinton carried in the 2016 election. In fact, as Wasserman noted, 14 of the 23 Republicans who represent Clinton districts voted for the bill.

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