(CNN) Illinois Rep. Dan Lipinski's primary loss earlier this week may soon mean there's less than a handful of Democrats left in the House who sometimes vote against abortion rights. And it's not a sure bet all of them will survive the November elections, raising the possibility that the Democratic caucus could soon be almost exclusively pro abortion rights.

And while that would put the caucus in sync with the Democratic Party's official platform on abortion, some Democrats fear that the loss of those anti abortion rights members might not bode well for Democrats' ability to hold onto seats — and make inroads — in redder parts of the country.

"Why is it important? We have to keep our majority," said Democratic strategist Dave Heller, who worked for Lipinski and has consulted for many other Democrats who oppose abortion rights.

Illinois' 3rd District, which Hillary Clinton won by 15 points in 2016, isn't at risk of falling into GOP hands. But that's not the case for Minnesota's 7th District, where House Agriculture Chairman Collin Peterson — perhaps the staunchest anti abortion Democrat in the House — is running for a 16th term. His district voted for President Donald Trump by a bigger margin than any other represented by a Democrat. That makes Peterson among the most endangered Democrats in 2020.

Decline in anti abortion rights Democrats

Classifying lawmakers as either supportive or opposed to abortion rights isn't black and white — it depends which legislation or action is being used as a litmus test.

But there's no question that the number of Democrats who vote against abortion rights has declined significantly over the last decade. During negotiations over the Affordable Care Act, 64 House Democrats voted for an amendment that would have prohibited women who receive federal insurance subsidies from buying abortion coverage. Most of those Democrats are either no longer in Congress or now vote in support of abortion rights. There are no Democratic women in the House who oppose abortion rights.

In the 116th Congress, just two House Democrats co-sponsored the Pain-Capable Unborn Child Protection Act, which would outlaw abortions after 20 weeks: Lipinski and Peterson. The same two lawmakers were the only Democrats to sign onto a brief submitted by 200 Republicans earlier this year urging the Supreme Court to overturn Roe v. Wade.

Peterson has the highest score from the National Right to Life -- 56% -- although not all of the votes the anti abortion rights group scores are explicitly about abortion. Lipinski has a 42% score.

Several other Democrats have sided with National Right to Life in 2019 and 2020 enough to earn them double-digit scores, but only one of them could be in trouble come November. Utah Rep. Ben McAdams has a 42% score.

Texas Rep. Henry Cuellar, who has a 27% score, just survived his biggest electoral hurdle — a well-financed primary challenge from his left. He isn't in electoral danger come November. Clinton carried his district by 20 points in 2016.

Rep. Ben McAdams, a Utah Democrat, participates in the Problem Solvers Caucus press conference in the Capitol in February.

Two vulnerable Democrats

The two Democrats who vote against abortion rights, to varying degrees, and could be in trouble in the fall are Peterson and McAdams.

McAdams, the former mayor of Salt Lake County, is a freshman who unseated GOP Rep. Mia Love in 2018.

"I support the teachings of my LDS faith that oppose abortion except in cases of rape, incest, danger to the mother's life and in certain other rare circumstances. I support the Hyde Amendment prohibiting the use of tax dollars to fund abortion, with certain exceptions," McAdams said in a statement Friday.

"Politicians are the last people who should be making decisions about abortions. Ultimately, decisions about terminating a pregnancy should made by a woman in consultation with her physician and others whose counsel she trusts like family and faith counselors," he added.

McAdams represents a district Trump won by nearly 7 points in 2016, which makes him a top Republican target. His strongest challenger, however, recently dropped out of the race.

State Sen. Dan Hemmert, a former aide to Republican Sen. Mitt Romney of Utah, said he'd reevaluated his ability to campaign and run his business late last year. "It's not the right time," he told the Salt Lake City Tribune in December.

McAdams ended the year with $1.8 million in the bank, giving him a financial advantage over the remaining Republicans in the race.

Peterson represents a sprawling, rural district in northwestern Minnesota that Trump carried by 31 points. After narrowly defeating an underfunded challenger who ran without national party support the past two cycles, Peterson is front and center on the radar of national Republicans, who've signaled support for a former lieutenant governor to take him on.

As one of the most conservative Democrats in the House, Peterson is known for bucking his party. He voted against the Affordable Care Act in 2010. More recently, he was one of just two House Democrats who voted against Democrats' gun background check legislation and against both articles of impeachment against Trump . Although he's close to speaker Nancy Pelosi, he was no fan of his party's presidential nominee in 2016. He told Roll Call that for the first time in his life, he couldn't bring himself to vote in the general election for president.

But when Peterson announced earlier this year that he'd seek a 16th term, Democrats breathed a sigh of relief.

"Every ounce of power that the Democrats have derives from Nancy Pelosi being the speaker of the House, and if we lose Collin Peterson, you lose Minnesota 7 forever," said Heller, the Democratic strategist, who's also working for the congressman.

The past several cycles, Peterson has asked the Democratic Congressional Campaign Committee not to spend on his behalf — for fear of unnecessarily nationalizing his race and taking resources away from contests where party money might have been more useful. But that might be different this year if he's up against former Lt. Gov. Michelle Fischbach and the outside GOP money her candidacy is likely to attract. Peterson ended the year with $1 million in the bank to Fischbach's $204,000.

Fischbach, who already has Trump's endorsement, is trying to attack Peterson for being insufficiently opposed to abortion rights. Fischbach's husband was the head of Minnesota Citizens Concerned for Life, and her mother is the co-director of the National Right to Life, which has endorsed her. Peterson has the backing of Democrats for Life, but the group doesn't have resources to spend in elections.

"He's a Democrat in a district where Hillary got 30.8% -- you've got to round up to get to 31 -- so there's nothing wrong with reminding people that you are a different kind of Democrat," Heller said.

"But is that the primary basis of our campaign? No," Heller said. "He's the chairman of the Ag Committee in rural Minnesota. If we are running on pro-life, then shame on us."