WASHINGTON – Doubts among Democratic voters about whether a woman can win the White House pose hurdles for Elizabeth Warren even as she has gained ground against 2020 primary rivals Joe Biden and Bernie Sanders, according to a USA TODAY/Ipsos poll.

Half of likely Democratic voters said a woman would have a harder time than a man running against President Donald Trump next year, the poll said. And while nearly nine in 10 of those voters said they would be comfortable with a female president, a smaller number, 76%, said their spouse or immediate family members were amenable to the idea.

And a mere 44% of voters likely to cast ballots in Democratic primaries thought their neighbors would be comfortable with a female commander-in-chief, according to the online survey conducted Aug. 28-30. Among Democrats, Republicans and unaffiliated voters, just 37% said they thought their neighbors would be comfortable with a woman president.

The survey was based on responses from 2,012 adults, including 923 Democrats and independents who say they "are probably or certainly" going to participate in the 2020 Democratic primaries.

The poll's credibility interval was 2.5 percentage points for all respondents and 2.9 percentage points for likely Democratic voters. A credibility interval is similar to a margin of error.

Warren, 70, has been drawing enthusiastic crowds in early voting states over the past several weeks, including last weekend when she got a standing ovation in New Hampshire, which holds the first-in-the-nation primary on Feb. 11.

Polls of voters nationwide and in early states showed that the Massachusetts senator solidified her place in the top tier of Democratic candidates over the summer. Former Vice President Joe Biden, 76, has maintained a sizable lead in the crowded field with Warren and Sanders, 78, consistently emerging as his nearest competitors.

Yet the question of whether gender could play a role in electability looms over the race nearly three years after Trump’s defeat of Hillary Clinton. Many voters see gender as an obstacle, not just for Warren but also for 2020 Democratic contenders Kamala Harris, 54, and Amy Klobuchar, 59.

"This country likes to go with tried-and-true and a white man is what they want, an older white man," said Democrat Natalie Hughes, who is African American.

The 55-year-old TSA screener from Landover, Maryland, said she is backing Biden because she believes he has the best chance to beat Trump. Hughes said she would vote for Warren if she is nominated but is concerned that "the American public won’t care that she’ll be more presidential, and I don’t think they’ll care that she’s more level headed or sane or more financially responsible than Trump."

"At this point in time, I don’t think this country is ready for a woman," said Hughes, who participated in the Ipsos poll.

Ipsos pollster Chris Jackson said many Democratic voters worry that independents and moderate Republicans might be less likely to back a female candidate in an election against Trump, although there may also be some "who have a measure of discomfort on their own and they’re just reluctant to voice it."

On the other hand, comfort with the idea of a woman in the White House has grown in recent months. The Ipsos poll found 83% of adults who identified themselves as Democrats and independents were "comfortable" with a female president – an increase of nine percentage points since June when Ipsos asked the same question.

Some Democratic primary voters who are wary of Warren as the nominee say their issue with her isn’t gender but that her progressive policies on health care, college debt and other issues could alienate swing voters in key states.

'I know how to fight'

Warren declined a request to be interviewed on question of gender issues in the 2020 race. But her campaign referred USA TODAY to her remarks during a July 30 Democratic presidential debate on CNN where she reminded viewers she unseated GOP incumbent Sen. Scott Brown in 2012.

"I get it. There is a lot at stake, and people are scared," she said. "But we can't choose a candidate we don't believe in just because we're too scared to do anything else. And we can't ask other people to vote for a candidate we don't believe in."

Warren echoed those sentiments when she was asked more directly about her electability at a New Hampshire rally Monday.

"I know how to fight, and I know how to win," she said. "But here’s another key part at last as I see it: I think what’s going to carry us as Democrats is not playing it safe."

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There were some signs of potential upside for Warren in the Ipsos data.

Because Warren is not as well-known as Biden and Sanders, she has room to grow her support as voters get to know her more, Ipsos' Jackson said. The poll found that as Democrats get better acquainted with her, they view her more favorably on traits traditionally seen as important to a nominee.

For example, when all likely Democratic voters were asked to compare Biden and Warren on their ability to stand up to Trump, 33% rated Biden as better, 27% rated Warren as better and 40% rated the two evenly. But when only the responses of voters familiar with all three were counted, 31% gave Warren the edge, while 26% said Biden was better and 43% rated them evenly.

When all these voters were asked to make the same head-to-head comparison between Sanders and Warren, 33% rated the Vermont senator better, compared with 24% who chose Warren and 44% who said they were even. Among more familiar voters, Sanders (26%) and Warren (27%) were rated virtually the same with 47% calling it a draw.

But the opposite theory – that less-engaged voters automatically ascribe qualities of toughness and decisiveness to the male candidates – is a red flag too, Jackson said.

“Sexism matters among the people who are less knowledgeable because, even up to the day of the election, we’re going to have people who go out and vote who don’t really know a lot,” he said. “And if sexism is moving those people then it can still matter, especially if the election’s close like it was in 2016 when 70,000 votes made the difference between Trump and Clinton.”

Trump won three states – Michigan, Pennsylvania and Wisconsin – by a combined 77,744 votes, giving him the electoral votes necessary to win the election.

A woman on the ticket

Many Democratic strategists say Clinton's flaws as a candidate were the main cause of her loss, not an unwillingness of voters to elect a woman. Clinton struggled to connect with blue-collar voters and was dogged by questions about her use of a private email server while she was secretary of state.

And party activists say the ascent of more female office holders in Congress and state offices across the country since 2016 – including in places Trump won – has improved the prospects for a female presidential candidate in 2020.

But some worry that not much has changed in the three years since a majority of white female voters helped the country elect a president who boasted about grabbing women’s genitals.

“We are making great strides as a nation when it comes to sexism, but I still think there are plenty of older men, in both parties frankly, who still think it’s not a woman’s time to be president,” said Grace Carrington, 53, a Democratic National Committee member from Coral Gables, Fla., who owns a home health care company.

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Carrington and others who gathered at the DNC’s summer meeting in San Francisco last month said the party needs a ticket that includes at least one woman.

“Women are voting in such large numbers that if there isn’t one on the ticket, there will be hell to pay,” said Carrington, who is black. “It cannot be two men, and it certainly can’t be two white men.”

That sentiment was echoed by Susan Eastlake, 73, a DNC member and national committeewoman from Boise, Idaho, who is optimistic that younger voters – who may be less likely to buy into gender stereotypes – could help elect the nation’s first female president.

“We’re in a totally different time (from 2016) when you have not just many female candidates but also many fresh faces,” she said. “People don’t really know Kamala Harris or even Elizabeth Warren except for maybe her policies. So it’s a chance to see people for who they are and not what their longstanding public image is.”

Breaking barriers

Overall, only 63% of all respondents said the country is ready to send a woman to the Oval Office, about the same level as 2008 when Barack Obama beat Clinton for the nomination, according to the Ipsos poll.

Warren supporter Tanae McLean, 48, of Mooresville, N.C., has doubts about whether voters are ready to nominate a woman for president.

The communications officer for a local school district thinks it's likelier today than it was at the beginning of the summer, given the momentum that's growing for Warren. But she worries gender is still an issue for some.

"I hate that. I think it’s ridiculous (in) this day and age that, that is even a question," said McLean, an independent. "We had a very qualified woman on the ticket in 2016 and I get the whole likability issue with Hillary Clinton, I get the baggage that came with Hillary Clinton, but I don’t think there was anybody on either side, right or left, that could say she wasn’t qualified and she wasn’t smart and she didn’t have what it takes to be a good president."

Clinton broke an important barrier by becoming the first female nominee of a major party, said Robby Mook, who managed Clinton's 2016 campaign.

“I don’t think that the idea of a woman running for president, the idea of a woman being nominated is novel anymore," he told USA TODAY.

“I think that any woman running for office, particular executive office, faces a special set of challenges that are hopefully going to be overcome at some point but are still very much there," Mook said. "For thousands and thousands of years, women were not always seen as the natural choice to take on an executive leadership role like this and a lot of that is still baked into our psychology."

The 2020 Democratic field included six women at one point. It's down to five after New York Sen. Kirsten Gillibrand, 52, dropped out in August.

Debbie Walsh, director of the Center for American Women and Politics at Rutgers University in New Jersey, said the difficulty of envisioning a woman in the White House is based on the simple fact that it hasn’t happened yet.

“We will cross this ultimate electability hurdle when a woman is elected and then we won’t have to question all the time whether a woman can be elected.”

Margaret Rand, 64, an ardent Warren supporter, has no qualms about the Massachusetts senator's ability to take on the president.

“I think she can beat Donald Trump because, first of all, she’s head and shoulders smarter than he is,” the retiree from Oskaloosa, Iowa, said during a recent interview. "He uses intimidation and she doesn’t have any problem standing up to people. She isn’t a shrinking violet. … She’s like the Energizer Bunny.”

Contributing: Kimberly Norvell, Des Moines Register