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

Wrote Cook’s House editor David Wasserman of the changes:

“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.

Two of the 20 changes affected members who actually opposed the AHCA: Leonard Lance of New Jersey and Mike Coffman of Colorado. Of Coffman, Wasserman wrote: “Coffman ended up voting against the AHCA, but his hesitation to announce his position likely won’t assuage voters who want to send a message to President Trump next year.”

Think about the changes the Cook Report made this way: To win back the House majority, Democrats need to gain 24 GOP seats. Twenty Republican seats just moved toward Democrats – in less than a day and with a single congressional vote.

That’s a big deal.

A caveat worth noting from Wasserman:

“For these Republicans, time is still on their side and healthcare reform can’t be disposed of soon enough. There are still 18 months before the 2018 election, whereas House Democrats eked out final passage of the ACA less than eight months before the 2010 midterms. These Republicans can’t afford a year-long Senate slog.”

Republicans then have to hope healthcare is totally passed and signed by President Trump by, say the end of this year. Knowing how slowly the Senate moves – and the policy and political complexities in the bill – that doesn’t seem terribly likely to me.