In addition to Runyan, the other lawmakers hailing from districts Obama won in 2012 include Reps. Mike Coffman (Colo.), Chris Gibson (N.Y.), Michael Grimm (N.Y.), Joe Heck (Nev.), John Kline (Minn.), Frank Lobiondo (N.J.), Gary G. Miller (Calif.), Erik Paulsen (Minn.), Scott Rigell (Va.) and Bill Young (Fla.)
The House Republicans who represent districts where Mitt Romney beat Obama by less than two points include Michael Fitzpatrick (Penn.), Scott Garrett (N.J.), Pat Meehan (Penn.) and Frank Wolf (Va.) The final target is Kerry Bentivolio (Mich.), who won reelection by less than seven points.
Many of these lawmakers have fought back serious challenges before, including Kline, Garrett, Wolf and Young. But others, who have served shorter terms in Congress, could face a barrage of activism and advertising on the issue.
Meehan, Israel argued, is the kind of lawmaker who would be particularly vulnerable to such criticism because 56 percent of voters in his suburban Philadelphia district believe abortion should be legal in all or most cases, while 34 percent say it should be illegal in all or most cases.
"Meehan consistently votes to restrict women’s freedoms and undermine women’s health care in a district that consistently supports women's freedoms and health care," Israel said in an interview last week. "We will hold extreme Republicans accountable on this issue."
National Republican Congressional Committee spokeswoman Andrea Bozek rejected Israel's analysis, suggesting Democrats will be vulnerable on the issue of the Affordable Care Act.
"Democrats are the party with the extreme positions when it comes to health care, and women are very concerned about the impact of Obamacare, not just on their health care but on their family’s health care," Bozek said.
Reproductive rights is less likely to play a key role in the most competitive Senate races, even though it was a key factor in both the Missouri and Indiana Senate contests last year. But depending on the candidates who make it through the primary, it could influence the outcome in a handful of races, including in Georgia and Kentucky.
Rep. Paul C. Broun (R-Ga.), who is eyeing his state's open Senate seat, took his name off Rep. Trent Franks' (R-Ariz.) bill last month after GOP leaders amended it to make exceptions if a woman is raped and reports it within 48 hours, or if a minor is the victim of incest. Broun said in a statement he was “extremely disappointed that House Republican leadership chose to include language to subject some unborn children to needless pain and suffering.”
And the match-up between Senate Minority Leader Mitch McConnell (R-Ky.) and Democrat Alison Lundergan Grimes offers a contrast in not just gender, but on abortion stances, though it's unclear whether either candidate will bring it up.
Democratic Senatorial Campaign Committee spokesman Matt Canter said that while he anticipates the broader issue of women's health is likely to come up in some races, he doesn't rule out "more Todd Akins who can't help explaining to women voters how their bodies work. Republican candidates still have a problem in this area."
National Republican Senatorial Committee spokesman Brad Dayspring said Democrats underestimate the extent to which voters back limits on abortion. "It’s a pro-life country and Republicans are a pro-life party," he said. "The key becomes candidates who talk about the issue in a compassionate and understanding way, rather than in a preachy way."
Regardless of how candidates talk about it, the issue of abortion could help influence the very swing voters both sides are courting. But whether it ends up helping usher more Democrats into office--or damage their chances if they overreach--remains to be seen.