On Tuesday, the House of Representatives will vote on the Pain-Capable Unborn Child Protection Act, a measure spearheaded by Reps. Trent Franks (R-AZ) and Marsha Blackburn (R-TN) that would cut off legal access to abortion services at 20 weeks after fertilization. It represents the most restrictive abortion bill to come to a vote in either chamber over the past decade. Here’s what you need to know about this attack on women’s reproductive rights — and how it fits into a broader, coordinated nationwide campaign to slowly chip away at abortion access: