A growing group of conservatives is concerned that many Republican presidential candidates may be ignoring female breadwinners in their campaigns, and that the results will show when the 2016 election rolls around.

"For years now, Democrats have been saying: We are focused on women in the workplace," Sabrina Schaeffer, executive director of the Independent Women’s Forum, which promotes conservative policies, told The Washington Post.

"For whatever reason, Republicans keep ignoring these issues. It’s the absolute worst thing they can do. They need to understand, engage and offer better solutions. They can’t be afraid."

The results of disregarding working mothers' needs has been showing in the past three presidential elections, reports The Post.

Nearly half of all working mothers voted to elect George W. Bush as president. However, by 2008, that share dropped to 40 percent for Arizona Sen. John McCain and in 2012, only about one-third voted for former Massachusetts Gov. Mitt Romney, both of whom lost their bids.

There are many new proposals that are being embraced by the party's policymakers and economists, but Republican strategists are concerned that many of the large crop of candidates are waiting until after the primaries to adopt the ideas in hopes of not alienating a segment of the party who believes at least one of a family's parents should stay home with their children.

Some conservative policymakers and groups have made proposals that could attract the female breadwinner vote, including a plan from an economist at the American Enterprise Institute, who has suggested allowing pregnant workers to claim part of their tax refunds early so they can have a paid maternity leave.

Meanwhile, a Heritage Foundation economist has called for changes to labor regulations so overtime pay can be traded for compensation days, and still other advocates are pushing for regulations to allow over-the-counter birth control.

Nebraska Republican Sen. Deb Fischer, meanwhile, wants to give companies a 25-cent tax credit for each dollar spent on employees' medical or family leave time.

"The public is watching," Fischer told conservative strategists earlier this month. "If we leave this narrative to our friends on the left, we don’t stand a chance."

Working mothers and women are also assuming a growing role and power in the United States' economy. According to the Pew Research Center, 40 percent of all American households are now supported by women, compared to 11 percent in 1960.

But even so, child care costs have nearly doubled in the past 50 years, reports the Census Bureau, reflecting another concern for working mothers. According to the Institute for Women's Policy Research, daycare costs about $22,000 a year annually in Washington D.C., and in the swing state of Virginia, it can run about $10,000 a year.

Democratic front-runner Hillary Clinton is already making women's issues a priority on the campaign trail, complaining about the lack of paid maternity leave in the United States, as well as the wage gap and lack of affordable daycare options, and strategists expect her to announce a policy agenda that will appeal to working mothers.

But only a few GOP candidates, like Carly Fiorina and Florida Sen. Marco Rubio, have called for policy changes. Fiorina, the former Hewlett-Packard chief executive officer, has announced an agenda that would reduce regulations on small business, which would help female entrepreneurs, and to allow over-the-counter birth control.

"For too long, the left has controlled this conversation," Fiorina said. "I think we need to have a conversation that’s both honest about how women are treated today and offers policy prescriptions to lift both women and men up."

Rubio and Utah Republican Sen. Mike Lee have proposed a tax credit of $2,500 per child, to be awarded in addition to existing tax breaks, to help families.

Douglas Holtz-Eakin, who was McCain's senior economic policy adviser during the 2008 election, told the Post that Republicans might be staying silent so they don't tip off the Democrats, as "anything we offer, the Democrats will offer 10 times that."

But when the Post asked Holtz-­Eakin, who is now the president of the American Action Forum policy institute, how McCain reached female breadwinners, he laughed and pointed out, "we didn't! We lost!"