The continuing internal House GOP division over the health-care legislation follows a Congressional Budget Office analysis that found the party’s initial ACA replacement could lower premiums for many younger and healthier consumers, but significantly raise costs for older working-age adults. Surveys have consistently shown the bill facing intense resistance among adults ages 50 to 64. In a late March Quinnipiac University poll, over three-fifths of those adults opposed the House GOP plan, more than in any other age group. Almost exactly half of adults in this age group said they strongly disapproved of the bill.

Likewise, in a recent ABC/Washington Post national survey, over three-fourths of adults 50 and older opposed allowing states to opt out from the ACA’s nationwide protections for insurance consumers with preexisting health conditions, as the latest version of the GOP bill allows. The same survey found three-fifths of adults in that age range opposed the bill’s provision allowing states to opt out of providing a menu of essential health benefits, such as covering substance abuse. Those sentiments loom over the pattern of opposition and hesitation on the bill that’s detailed in an unofficial whip count published by The Hill.

As of Monday afternoon, that count identified 22 House Republicans opposing the bill, potentially enough to sink the measure. Just eight of those 22 declared opponents represent districts that Hillary Clinton carried last fall. Fourteen represented districts that Trump carried. And in 15 of the districts, Trump performed better than Romney did in 2012.

Those numbers mean the bill’s opponents are still more likely than the GOP caucus overall to hold seats that Clinton carried: A little more than one-third of the opponents are in such split-ticket districts, compared with only about 10 percent of all 238 House Republicans. But the number of opponents from split-ticket districts is more modest than many might have expected—and limited enough that most of the declared opponents of this urgent priority for Trump represent districts that he carried, often by a stronger margin than Romney did four years ago.

Age may help explain why so many Trump-district Republicans are resisting him. Fully 17 of the 22 declared opponents to the legislation hold seats where the median age exceeds the national average of 37.8 years old. Sixteen of the 22 hold seats where the share of seniors 65 and older exceeds the national average of 14.9 percent. In another three districts, the share of seniors is just 1 percent or less than the national average. That means over three-fourths of the bill’s declared House Republican opponents represent districts older than the national average. That significantly exceeds the nearly three-fifths of all House Republicans who represent such greying districts, according to Atlantic calculations. (Updates to the whip count published Tuesday morning did not significantly change any of the patterns described here.)