This is the all-female number-crunching team that delivered the House to Dems | McClatchy Washington Bureau

The hour was growing late one March night and still neither party knew who had won a key special election in Pennsylvania, where only a few thousand votes separated the candidates. So Dan Sena — executive director of the Democratic Congressional Campaign Committee — turned to his chief number-cruncher for answers.

He handed her a note that showed how many absentee ballots each county had yet to count in the race between Democrat Conor Lamb and Republican Rick Saccone.

“I took the Post-It note, and with some number crunching and math, found we would probably gain 300 votes,” Claire Low, the DCCC’s targeting and analytics director, would say months later.

Sena would soon publicly declare victory, catching reporters and political operatives by surprise in a contest that still looked too close to call. But he knew the members of his data and analytics team understood the numbers and trusted them to make the right call.

It wouldn’t be the last time that they would prove him right.

At every step of the 2018 election, House Democrats at the DCCC relied heavily on a data and analytics team that guided the committee through two years of tumultuous politics and an ever-fluctuating path back to the majority.

The results speak for themselves: Democrats gained 40 House seats, a gargantuan total for a party once hoping to simply eke out 23 seats necessary for a majority. They were the party’s largest House gains in a single campaign since 1974.

DCCC officials were also delighted that, in an election where the party earned overwhelming support for women and benefited from a surge of female candidates, the team analyzing the numbers behind-the-scenes was also led by three women: Rosa Mendoza, who ran the analytics team at the group’s independent expenditure operation, Amber Carrier, the group’s director of polling and modeling, and Low, the targeting director.

“We set out to do things differently, and I’m proud that we hired a historically diverse DCCC team this cycle, including a women-run polling and analytics team that is the best in the business,” Sena said.

The data and analytics team delivered a litany of important strategic insights for House Democrats, such as prioritizing a race in Virginia’s 7th Congressional District (where the party’s nominee was a narrow victory) over one in Virginia’s 5th Congressional District (where the Democrat lost by more than six points), or warning candidates that many Cuban-American voters weren’t as negative about President Donald Trump as they might expect while insisting that candidates in Texas mention the GOP leader when communicating with suburban women.

They also discovered approaches with potentially important 2020 implications, such as the importance of a positive messages to engage many communities of color.

The women leading the data team, in fact, even helped recruit other women to run in battleground races, including Congresswoman-elect Debbie Mucarsel-Powell in Florida’s 26th Congressional District. When Murcasell-Powell visited the committee headquarters, she received a detailed briefing about the nature of the district — and how she could possibly defeat incumbent GOP Rep. Carlos Curbelo.

“On the analytics side, we walk them through the numbers and we walk them through the demographics and say, ‘This is what you need to win, and this is your path to victory, and this is how this can become a reality,” Mendoza said. “I remember Debbie had come in and asked, ‘Is this just going to be about Trump?’ And we actually spoke to her about Curbelo’s at-that-point health care views and the actual action he had taken on the bill and how it detrimentally impacted his community. So it wasn’t just going to be about Trump.”

Throughout the campaign, House Democratic candidates focused on the GOP’s attempted repeal of the Affordable Care Act and its passage of a tax-cut law. The relentless focus on pocketbook issues — while avoiding a fixation on President Trump — paid off for a party often criticized for lacking a coherent message or being distracted by culture war fodder.

Their unwavering focus wasn’t by accident: Throughout 2017 and 2018, the DCCC’s data team conducted extensive research on the GOP’s health care legislation and later its tax law, devising the messages that would best resonate with voters. For health care, for example, research showed the message needed to connect directly with people’s lived experience of rising health care costs and the number of people who would lose insurance in their community. Criticism of the tax law, meanwhile, worked best when not emphasizing big corporate tax cuts but the harmful effect it could have on Social Security and Medicare, and big breaks for specific corporations such as pharmaceutical companies.

“Once you drop them in and compare to them to some of the weaker arguments and platforms they could be running on, there was no comparison,” Carrier said.

She said the DCCC gave this research to the candidates and let their own campaigns decide what worked best for them. By and large, as evidenced by the TV ads they ran, the candidates followed the team’s recommendations.

One other recommendation from the group: To win over voters of color, candidates needed to emphasize a positive message that talked about concrete ways in which Democrats could improve their lives.

“Through our research, we found that going negative was really not the way to go,” Mendoza said. “Presenting Trump and showing, look at all the negative things he said about us, the rapists and the so-and-so ... it just didn’t increase enthusiasm. It wasn’t motivating them as much as presenting them with a better outlook that their children could have.”