It was no accident the first TV ad the National Republican Senatorial Committee ran to help Republican Carly Fiorina’s campaign against Sen. Barbara BoxerBarbara Levy BoxerKamala Harris on 2020 presidential bid: ‘I’m not ruling it out’ The ‘bang for the buck’ theory fueling Trump’s infrastructure plan Kamala Harris endorses Gavin Newsom for California governor MORE (D-Calif.) focused on women voters.

“They’ve already got the Republican vote, they’ve got the white male fiscal conservative vote,” said Republican strategist Karen Hanretty. “It’s all a numbers game, and women are the smart strategy.”

“It’s clear that in every public poll, Boxer has performed better with women than Fiorina has,” said veteran Republican strategist Ken Khachigian, a volunteer adviser to Fiorina’s campaign. “It seems pretty obvious that it’s important to chip away a few points here and there away from Barbara Boxer and towards Carly amongst women.”

Traditionally, a higher percentage of women voters go to the ballot box compared with men, particularly during midterm elections, according to the nonprofit group Women's Voices, Women Vote, which has close ties to Bill and Hillary ClintonHillary Diane Rodham ClintonHillicon Valley: Trump's exclusive interview with Hill.TV | Trump, intel officials clash over Russia docs | EU investigating Amazon | Military gets new cyber authority | Flynn sentencing sparks new questions about Mueller probe READ: President Trump’s exclusive interview with Hill.TV Keeping up with Michael Avenatti MORE. But unmarried women, who overwhelmingly prefer Boxer, go to the polls far less than married women. But with the help of Emily’s List and other groups, Boxer secured an advantage among women overall, early on.

Boxer is a favorite among unmarried women voters by a whopping 32 points, 60-28, according to Page Gardner, an ex-Clinton campaign aide and founder of Women’s Voices, Women Vote and its sister organization, the Women’s Voices, Women Vote Action Fund. Married women — who tend to be more centrist or right-leaning than unmarried women voters — favor Boxer 49 to 42 percent, she said.

“There’s an enormous difference and enormous gap between unmarried and married women,” Gardner said. Men favored Fiorina by a couple of points and women overall favored Boxer by 17, she added.

Fiorina has done an effective job of concentrating on fiscal issues that appeal to centrist voters as opposed to potentially divisive social issues like Tea Party Senate candidates such as Rand PaulRandal (Rand) Howard PaulConservatives left frustrated as Congress passes big spending bills Senate approves 4B spending bill Some employees' personal data revealed in State Department email breach: report MORE and Christine O’Donnell, said Jennifer Duffy, a senior editor at the Cook Political Report.

“She’s running more on the need to change and change for the purposes of the deficit and keeping taxes low and things like that and I think that is a message that appeals to the middle,” Duffy said.

But Boxer and her supporters have hammered Fiorina’s pro-life views, her skepticism over climate change and opposition to an assault weapons ban, among other social issues.

Fiorina’s anti-abortion views particularly helped Boxer as well among women. “It is a threshold issue with a lot of women” in the state, said Garry South, a California Democratic strategist who is not affiliated with Boxer’s campaign.

“I’m quite familiar with the California electorate and it’s pretty hard to sell an anti-abortion woman candidate to … women [in the electorate] who are 70 percent pro choice,” said South, who helped lead former Gov. Gray Davis’s 1998 and 2002 campaigns.

Both candidates have been labeled by critics as extremists.

“If there were a legitimate centrist running against Barbara Boxer she would probably get beat,” South said. “But if you accept Carly Fiorina’s argument that Boxer is too far to the left for California then Fiorina is five times further to the right than Boxer is to the left.”

“Clearly her viewpoints are going to be right of center, but I also don’t see her as a strict partisan," Hanretty countered. "Certainly not to the partisan extent of Barbara Boxer. She is much more independently minded."

Fiorina from the start faced an uphill fight in trying to become the first Republican senator in blue California since 1992 despite the Republican surge this midterm election and Boxer's perceived weaknesses as a legislator.

The $3 million ad buy from the NRSC underscored that Republicans viewed the race as winnable heading into the final week before Election Day.

“Republicans would not have spent $3 million this week if they didn’t think this was still doable,” Duffy said.

But Fiorina’s chances may be fading as a series of recent polls have Boxer ahead beyond the margin the error.

A Field Poll released late Thursday had Boxer leading by 8 points, 49 to 41, among likely voters. A Suffolk University poll released earlier in the week had Boxer up by 9, a CNN/Time poll had her up by 5 and one by the Los Angeles Times had her up by 8. A Rasmussen survey, on the other hand, had it closer, with Boxer up by three. Real Clear Politics and the Cook Political Report also have rated the race as a toss up and Republicans have touted internal numbers that indicate the race is a statistical tie.

Fiorina has struggled to keep pace with Boxer’s fundraising and spending advantage.

The $3 million NRSC ad buy, plus a $1 million loan Fiorina gave her campaign recently, was meant to allow her to make up some ground and go toe-to-toe in spending with Boxer during the campaign’s last week.

Boxer has raised more than $26 million, compared with close to $18 million for Fiorina, according to the Center for Responsive Politics (CRP).

Outside groups have helped to narrow that fiscal advantage somewhat.

The race ranks eighth this cycle in terms of spending by outside special-interest groups, totaling roughly $11.8 million, according to CRP. That includes more than $3.5 million in ads run opposing Boxer and about $1.2 million run opposing Fiorina. The U.S. Chamber of Commerce alone has spent $4.9 million in the race.

Both sides have blamed the other for avoiding issues on the campaign trail.

“Boxer if you follow her whole campaign it’s been her goal to distract away from economic issues,” Khachigian said.

Fiorina is “running on the economy because she can’t run on the social issues,” South said.

Boxer has been hitting Fiorina all campaign long about outsourcing at Hewlett-Packard when Fiorina was CEO of the company. Fiorina’s campaign has fired back with a campaign ad this week noting Boxer’s visit Tuesday to Cisco, another company that has been criticized for outsourcing jobs.

A Boxer victory could preserve two things for Democrats in the next Congress: a slim majority overall and a potentially combative environmental debate on the Environment and Public Works Committee, which Boxer chairs.

Boxer’s hometown newspaper, The San Francisco Chronicle, made a surprising non-endorsement in the race, citing her combative style as a reason she was not given the lead in trying to craft a bipartisan deal on climate policy this Congress.

“There’s very little willingness or opportunity for a fair hearing so most people don’t even bother to go check that box,” said Stephen Brown, vice president and counsel for federal affairs for the independent petroleum refiner and marketer Tesoro Corporation.

Tiernan Sittenfeld, legislative director for the League of Conservation Voters, countered that Fiorina’s skepticism about climate change and support for the state’s Prop 23 ballot initiative is “breathtaking and shows how out of touch she is with the people of California.”