As of Thursday morning, the Club for Growth had not decided to key-vote the legislation. The group's recommendations often parallel that of Heritage Action.
The Heritage Action move is the latest twist in a drama over farm policy that has bedeviled House GOP leaders in recent weeks.
The House decided not to risk moving a five-year $957 billion farm bill, which was reported out of the Agriculture Committee, for fear of a conservative backlash, and had to pull a one-year extension earlier this week from the floor when the votes were not there.
House leaders on Wednesday realized that they could not pass the drought bill under suspension of rules, which requires a two-thirds majority.
The Heritage Action move raises the possibility that a majority of members might not vote for the bill. Republican Study Committee head Rep. Jim Jordan (R-Ohio) told The Hill he will vote against the measure.
Environmentalists are opposed to it because it cuts $639 billion from conservation programs, so some liberal defections can be expected. Rural members hoping for a five-year farm bill could also vote no to sustain their push for a more expansive measure.
The Senate does not plan to take up the drought bill if it does pass the House on Thursday, precisely to keep up pressure to pass a farm bill. The Senate cleared a five-year bill in June.
— This story was last updated at 11:47 a.m.