If those 16 are likely against the AHCA, Ryan can only afford five more defections. And those defections are most likely to come from where the 16 do: the poles of the Republican caucus — its most moderate members and its most conservative members.

Along with Katko, Lance and Ros-Lehtinen, 20 other House Republicans live in congressional districts where Clinton won. About 50 House Republicans are associated with the moderate Tuesday Group, which includes Dent and MacArthur. (There is substantial overlap between those associated with the Tuesday Group and members from Clinton districts, so the bloc of House moderates numbers about 60.)

But while “no” votes may come from the more moderate wing of the party, worried the legislation is too conservative, there is a large bloc of members who are skeptical that the bill is conservative enough. There is no public, formal list of the members of the House Freedom Caucus.3 But at least 30 House members have publicly associated themselves with the group, and it is a hot bed of reservations about this bill. For example, Mo Brooks of Alabama, a Freedom Caucus member, called the legislation, “the largest welfare program sponsored in the history of the Republican Party.” And as noted above, four Freedom Caucus members are already very resistant to the bill.

That’s a lot of members — at least 50 moderates and at least 25 solid conservatives — to keep in line.