Democrats made one thing clear Tuesday, on the first night of the Democratic National Convention: In 2012, women's health issues are taking center stage.

"We believe that a woman considering an abortion should not be forced to have an ultrasound against her will," NARAL Pro-Choice America president Nancy Keenan told a roaring crowd. "We believe that rape is rape. And we believe that there's no place in that room for politicians—especially politicians who don't know how women's bodies work."

Keenan spoke after two dozen female House Democrats gave remarks focused on contraceptives and reproductive health. And she preceded the first lady, who also dove into the subject, saying that her husband "believes that women are more than capable of making our own choices about our bodies and our health care."

Behind the scenes, candidates and outside groups have poured at least $16.8 million into abortion-related advertising during the 2012 cycle, more than two-thirds of which has come from the Obama campaign and its allies.

The total figure is nearly equal to the amount spent on Medicare-related advertising in 2012 and three times as much as groups have spent on immigration-related spots, according to the media tracking firm CMAG/Kantar Media.

At that point in the 2008 election cycle, CMAG had not seen any presidential campaign ads that touched on women's health and reproduction.

“This really is different,” said Marjorie Dannenfelser, president of the Susan B. Anthony List, which opposes abortion. “There were fits and starts of this conversation in 2008, especially because you had so many women running for office. This time it feels more extended and like an issue that will move voters.”

Last week her group launched a $150,000 ad buy in Missouri, meant to highlight President Obama's "extreme abortion record" and demonstrating that antiabortion groups do not plan to sit on the sidelines this year.  Dannenfelser has spent the past few weeks crisscrossing the country on a 30-stop bus tour, the group’s first during a presidential contest. The Susan B. Anthony List’s membership has grown from 143,000 in 2008 to 365,000 in 2012.

“These issues have been magnified, elevated and catapulted up to the presidential level,” Keenan said in an interview.

What began with a fight last year over defunding Planned Parenthood — a battle that nearly shut down the federal government — became a fierce debate over government-mandated coverage for contraceptives. Abortion restrictions, which states previously passed with little fanfare, began blowing up into national controversies.

A Mississippi push to declare personhood as beginning at conception drew attention nationwide because some critics saw it as a de facto ban on abortion. Virginia’s proposal to require a transvaginal ultrasound before a woman could have an abortion sparked a national outcry from abortion-rights supporters, though six states already had such laws in place.

Then a comment by Rep. Todd Akin (R-Mo.) — his immediately discredited assertion that “legitimate rape” rarely leads to pregnancy — revived the issue.

Advocates on each side see a political advantage to continuing the debate. For Republicans, many polls show that abortion opponents consider it a more important factor in their vote than do abortion-rights supporters.

At the same time, Democrats seem to have found a foothold. In a Pew Research Center poll in March, 49 percent of voters said the Democratic Party would do a “better job” representing their views on abortion. For the Republican Party, that number stood at 33 percent.

“This issue of women’s health is going to play a much bigger role nationally than it ever has,” said Democratic pollster Anna Greenberg. “I’m working on multiple races where we’re going to run on this.”

The wave of Republicans elected in 2010 came to Washington ready to fight back against Obama’s health-care law, which many considered a step toward the public funding of abortion. They set their sights on the country’s largest abortion provider: Planned Parenthood.

“We have repeatedly said that Obamacare is the largest expansion of abortion since Roe v. Wade, and that’s not hyperbole,” said Charmaine Yoest, president of Americans United for Life. “By integrating abortion into health-care reform, it was just a seismic kind of shift. That’s why we’ve really mobilized people to understand what is at stake in this election.”

Since 2007, Rep. Mike Pence (R-Ind.) has introduced legislation that would cut off Planned Parenthood’s federal funding. Bill after bill languished in committee, never receiving a House vote; one amendment he offered failed to get a single co-sponsor.

But Republicans in this Congress made it a priority to eliminate Planned Parenthood's funding. The issue nearly shut down the federal government when Obama refused to allow such a provision into the national budget.

It also became a central campaign issue. Romney is the first Republican presidential candidate to pledge to cut funds to Planned Parenthood. His running mate, Rep. Paul Ryan (Wis.), voted for legislation that would have done so.

“We’ve seen in this presidential election already three ads about defunding Planned Parenthood,” said Cecile Richards, president of the Planned Parenthood Federation of America and Planned Parenthood Action Fund. “That’s never happened before that I can remember. John McCain never talked about defunding us. George Bush never did that, either.”

The Planned Parenthood Action Fund has doubled its campaign spending since 2008, increasing advertising and on-the-ground activity.

The goal for both sides is to turn women’s health into a winning issue at the polls in November. Greenberg, working with Democratic candidates nationwide, argues that extending the argument beyond abortion to include contraceptives will work well for her party.

“We’re having a national conversation about the most bizarre issues: the definition of rape and the largely settled debate over the use of birth control,” she said. “It prevents Republicans from having the conversation they want to have about the economy.”

Yoest makes the opposite case. Her group, Americans United for Life, has been involved in passing 19 state abortion restrictions level this year. She said she has seen energy among her supporters.

“It’s a dangerous strategy for [the Obama administration] to walk so far out on an aggressive pro-abortion strategy,” she said. “There’s been a backlash.”

Correction: A previous version of this article used advertising data from Aug. 28, 2012 showing spending on abortion-related ads to be nearly double that of spending on Medicare-related ads. Newer spending data, obtained Sept. 5, shows the two amounts to now be nearly equal.