PHILADELPHIA — On Friday night, Katie McGinty stood on the stairs at Pennsylvania 6, a dimly lit downtown bar, and exclaimed, “We have some girl power in the house tonight!”

To the left of the Pennsylvania Democratic Senate hopeful stood four incumbent female senators: Debbie Stabenow of Michigan, Jeanne Shaheen of New Hampshire, Tammy Baldwin of Wisconsin and Mazie K. Hirono of Hawaii. The Keystone State marked the group’s second stop on a campaign swing to boost the ranks of the chamber’s female Democrats.

It was also the first time since the Democratic National Convention here in July that a group of female senators hit the campaign trail. The focus was on three battleground states — North Carolina, Pennsylvania and New Hampshire — that could determine whether the Senate flips to Democratic control next year.

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Six of the 11 competitive Senate races featured in Roll Call’s Election Guide involve major-party female candidates. Democrats running in Pennsylvania, Nevada and Arizona could become the first women to represent those states in the Senate. Catherine Cortez Masto of Nevada would also be the first Latina senator.

“Men have been campaigning against men forever,” Stabenow said. “It’s important to support women who share our values.”

There are fewer prospects for new Republican female senators next year. The current election cycle features many more GOP incumbents up for re-election, including Sens. Kelly Ayotte of New Hampshire and Lisa Murkowski of Alaska.

There are currently six Republican women in the Senate, compared to 14 Democrats. The GOP incumbents have also hit the trail for their colleagues: Shelley Moore Capito of West Virginia and Joni Ernst of Iowa campaigned together with Ayotte in March, and Ernst returned to New Hampshire in September.

Ayotte is also in the unique position of facing a female challenger, Democratic Gov. Maggie Hassan. The race is rated a Tossup by The Rothenberg & Gonzales Political Report/Roll Call. Since 1960, only 13 other Senate races have featured two women as the top candidates, according to data from Rutgers University’s Center for American Women and Politics.

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Shaheen, who helped organize the Democratic group’s three-state campaign swing with Baldwin, dubbed it their “women’s tour.” Though stumping for colleagues is a ritual, members of the group noted that this cycle is different.

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“There’s so many of them!” Baldwin said in reference to the number of Democratic female challengers this cycle as she stood outside the bar that hosted the McGinty event.

Baldwin chairs the Women’s Senate Network, which was established in 2001 as part of the Democratic Senatorial Campaign Committee. In that capacity, she serves as a resource for female candidates and has given each one her phone number.

“Some have taken me up on the offer to talk anytime more than others,” Baldwin said. “And there’s some that I check in on, if know that it’s been a tough week or that there’s a great poll they want to celebrate.”

Shaheen and Stabenow also said they talk with the female challengers.

“We’re trying to be helpful in every way that we can, and if it’s advice on how to message or if it’s ‘Can you come help me campaign? Can you help me raise money?'” Shaheen said.

The lawmakers have been an valuable resource for McGinty, locked in a tight race with Republican Sen. Patrick J. Toomey.

“They have been so helpful to me in everything from, at the outset, talking through the challenges in balancing a campaign and family life, and helping me to prepare my own girls for what the rigors of this are like, to opening their own Rolodexes and helping us build the resources for this campaign, to literally getting on the road with me,” McGinty said.

This cycle has another element that sets it apart: the opportunity to campaign for a female president.

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The events in Philadelphia, New Hampshire and North Carolina aimed to boost both Senate candidates and Hillary Clinton’s presidential campaign. 

“I think the fact that we have a woman running for president has just sort of focused us in on the importance of adding women’s voices and experiences to the process of governing,” Stabenow said. 

The senators campaigning over the weekend are trailblazers in their own right. Each is the first woman to represent her state in the Senate. Shaheen is the first woman in U.S. history to be elected both a governor and senator. Hirono is the first Asian-American female senator. Baldwin is the first openly gay person elected to the Senate.

Rachel Thomas of EMILY’s List, a group that backs female Democratic candidates who support abortion rights, said having the female senators campaign together is a valuable asset.

“It really highlights the importance of having women in these offices in the Senate,” Thomas said, “because they bring perspectives that haven’t been there before.”

Contact Bowman at bridgetbowman@rollcall.com and follow her on Twitter @bridgetbhc.