The divide between Republicans and Democrats over abortion is deeper than ever. Activists on both sides foresee a 2016 presidential campaign in which the nominees tackle the volatile topic more aggressively than in past elections.

Friction over the issue also is likely to surface in key Senate races. The opposing camps will be further energized by Republican-led congressional investigations of Planned Parenthood and by Supreme Court consideration of tough anti-abortion laws in Texas.

In the presidential race, Democratic front-runner Hillary Clinton is a longtime defender of abortion rights. In contrast, nearly all the GOP candidates favor overturning the Supreme Court decision that legalized abortion nationwide. Some contenders, including Sens. Ted Cruz and Marco Rubio, disapprove of abortions even in cases of rape and incest.