With a massive field of vulnerable House incumbents to defend and limited resources to go around, Republicans are readying for a painful round of political triage — deciding which lawmakers are worth trying to rescue, and which ones need to be cut loose to fend for themselves in November.

GOP officials say as many as 45 Republican-held seats are at serious risk, making it impossible to salvage each one in the costly scramble to protect the party’s 23-seat majority— especially those members who have waged sluggish campaigns and posted lackluster fundraising totals.