Mitt Romney describes abortion as an issue more relevant to the legal system than the presidential election. “This is a matter in the courts,” the Republican candidate told CBS News on Monday. “It’s been settled for some time in the courts.”

But the current campaign is replete with evidence that abortion remains a vibrant political issue. 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 twice the amount spent on Medicare-related advertising in 2012 and three times as much as groups have put toward immigration-related spots, according to the media tracking firm CMAG/Kantar Media.

At this point in the 2008 cycle, CMAG had not seen any presidential campaign ads that touched on the issue.

“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.”

On Tuesday, Dannenfelser’s group announced a $150,000 television campaign in Missouri to highlight President Obama’s “extreme abortion record.” She is 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.

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 an abortion sparked a national outcry from abortion-rights supporters, even 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.

“These issues have been magnified, elevated and catapulted up to the presidential level,” said Nancy Keenan, president of NARAL Pro-Choice America.

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 on the subject failed to get a single co-sponsor.

But Republicans in this Congress made it a priority to eliminate the abortion provider’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 Planned Parenthood’s funding. 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 abortion restrictions at the state level this year. She has seen the 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.”