It was supposed to be an exhibition of the candidates who would set the Democrats on the path back to political relevance. Instead, a recent “unity tour” of the party’s brightest stars became the latest staging ground for a fight over how to recraft the Democratic message after its most crushing defeat in a generation.

The trouble began when the Democratic National Committee arranged a political rally for Heath Mello, a competitive candidate for Omaha mayor, to its swing through the heartland.

As a Nebraska lawmaker, Mello supported a ban on abortions after 20 weeks, and he co-sponsored a 2009 bill requiring abortion providers who perform an ultrasound before the procedure to display the image of the fetus for the woman.

The backlash came swiftly.

“[For] the DNC to embrace and support a candidate for office who will strip women – one of the most critical constituencies for the party – of our basic rights and freedom is not only disappointing, it is politically stupid,” said Ilyse Hogue, the president of NARAL Pro-Choice America.

A Planned Parenthood spokeswoman said that the organization “will hold any political party, any candidate for public office, and any elected official accountable for not standing up for reproductive rights”.

The outcry caused Mello, whose voting record has since become more liberal on reproductive rights, to promise that his personal views would never lead him to support new abortion restrictions. In a hasty statement, Tom Perez, the newly chosen president of the DNC, called on all Democrats who are personally anti-abortion to do the same.

But for some in the party still convinced that the emphasis on social justice cost them dearly in November’s elections, these episodes have stoked new concerns for Democrats as they grope for a credible path back to the majority.

“There are some very substantial consequences for trying to demand an ideological purity test of the candidates who are stepping forward to try to win back some of these swing seats,” said Earl Pomeroy, a former Democratic congressman who represented a conservative North Dakota district for 18 years. Pomeroy, now a political consultant, was among the Democrats who voted to limit federal spending on abortion coverage.

Everybody has their litmus tests. And we all make our compromises Howard Dean

“The price for these swing seats, in order to recover some of the seats that Democrats have lost, will be: who can appeal to the independent voter right in the center of the ideological spectrum?” he said.

A local race in Omaha is not the only stage on which these fights have played out.

In Virginia, Tom Perriello’s campaign for governor has fueled similar questions. A champion of Barack Obama’s agenda during his single term as a congressman from south-west Virginia, Perriello is running as the liberal challenger to the other Democrat, lieutenant governor Ralph Northam, seeking the governor’s seat.

Perriello’s record on abortion rights, however, includes a 2009 vote for the Stupak Amendment, a failed attempt to impose a broad ban on private insurance coverage for abortion by amending the Affordable Care Act. Perriello later joined Democrats who pressured Obama to block federal insurance subsidies for abortion coverage through executive action.

In May 2016, Perriello called his vote for Stupak the worst vote of his career. He apologized for his vote this January in a lengthy Facebook post as progressives questioned whether he still opposed federal funds for abortion. One headline, on the pro-abortion rights news site Rewire, read: “Democrat With Anti-Choice Background Enters Virginia Gubernatorial Race.”

The stir caused by their voting records hasn’t cost either man significant support. Mello’s sold-out rally with Sanders went ahead as scheduled. And this week, Perriello notched the support of another beloved progressive, Senator Elizabeth Warren.

Heath Mello waves to supporters at a rally in Omaha last week. Mello says his personal views would never lead him to support new abortion restrictions. Photograph: Charlie Neibergall/AP

But some saw these episodes as warning signs that Democrats were gravitating toward the same kinds of purity tests that have riven the Republican party.

On Tuesday, DD Guttenplan, the editor-at-large of The Nation, wondered how “a party that sets the bar so high … can ever hope to become a majority.”

Pomeroy went further, saying: “I don’t have a lot of agreement with advocacy groups that want to pull candidates well out of the mainstream, where they need to be to win an election.”

Supporters of reproductive rights reject the idea that abortion rights are out of favor with the mainstream. In 2016, public support for abortion to be legal in all or most cases was at its highest in two decades, at 57%.

To groups like NARAL, the party’s decision to throw its weight behind a politician with a spotty reproductive rights record not only broke with party promises – it sent a hostile message to the women who have been showing up in force to oppose Trump and his policies.

“Women are the most energized part of the Democratic party’s base right now,” said Kaylie Hanson Long, NARAL’s national communications director. “They’re flooding town halls. They have made the vast majority of phone calls into congressional offices.” (Early polls have found liberal women to be somewhat more likely to get involved in activism since Trump’s election.)

“Reproductive rights were the tip of the spear of the Women’s March, which touched communities all across the country,” Long continued.

It’s reproductive rights advocates, she pointed out, who have forced some of the most memorable confrontations with Republican lawmakers this month as they faced hostile constituents. On April 14, a testy town hall with Senator Jeff Flake of Arizona erupted in cheers after a young woman challenged his vote to remove Planned Parenthood from the nation’s family planning safety net.

Nevadans booed Senator Dean Heller a few days later for refusing to state his position on federal funding for Planned Parenthood. “I will protect Planned Parenthood,” Heller said later in the event. “I have no problems with federal funding for Planned Parenthood.”

Heller, who is up for re-election in 2018 before an electorate that only narrowly rejected Trump, later flip-flopped.

But his town hall remarks are proof, in the eyes of reproductive rights groups, that Republicans’ stance on Planned Parenthood and abortion rights can be a winning issue for Democrats. In another sign, some rank-and-file Republicans have asked party leaders to avoid a showdown with Planned Parenthood in any legislation that repeals Obamacare.

But Marjorie Dannenfelser, president of Susan B Anthony List, an anti-abortion political action committee, doesn’t believe it’s Republicans who face a problem. While someone like Heller “is no profile in courage”, she noted that he had not changed his vote on key issues.

“Just a few years ago, there was bickering in the Republican party about, Are we going to allow people in the tent that disagree with us on this issue?” she said. “Now, Democrats are having that same conversation. The difference is … they are shunning the voters we’re happy to have.”

In addition to confronting Republicans, some of those newly energized reproductive rights advocates have targeted middle-of-the-road Democrats.

Planned Parenthood volunteers in West Virginia are calling for Senator Joe Manchin, who is seeking re-election in a state Trump carried by 42 points, to change his past position and support federal funding for Planned Parenthood.

This month, Manchin was photographed posing with an “I Stand With Planned Parenthood” poster. But his office has ignored requests to clarify his current stance on Planned Parenthood’s federal funding, including a request this week from the Guardian.

There are some who argue that flashpoints like these are healthy for the Democratic party.

“I actually think this debate is incredibly helpful, because it’s happening out in the open,” said Howard Dean, the former DNC chair and presidential candidate. By contrast, Dean said, many moderate Republican lawmakers have been simply purged from their party.

Dean added that he doesn’t think the recent clashes were anything new to Democratic politics.

“It’s perfectly permissible for women who care deeply about women’s rights to say: I don’t want anything to do with anti-abortion candidates,” he said. “Abortion is a human rights issue. It’s about whether women get treated equally in society.”

But an anti-abortion Democrat, Dean said, is always preferable over a Republican.

“So Bernie has no problem supporting an anti-abortion candidate. Everybody has their litmus tests,” he said. “And we all make our compromises.”

An earlier version of this article misspelled Tom Perriello’s last name.