NEW YORK — With a deeper-than-ever split between Republicans and Democrats over abortion, activists on both sides foresee a 2016 presidential campaign in which the nominees tackle the volatile topic more aggressively than in past elections.

Friction over the issue also is likely to surface in key Senate races. And the opposing camps will be further energized by Republican-led congressional investigations of Planned Parenthood and by Supreme Court consideration of tough anti-abortion laws in Texas.

“It’s an amazing convergence of events,” said Charmaine Yoest, CEO of the anti-abortion group Americans United for Life.

In the presidential race, Democratic front-runner Hillary Clinton is a longtime defender of abortion rights and has voiced strong support for Planned Parenthood as it is assailed by many Republican officeholders.

In contrast, nearly all of the Republican candidates favor overturning the Supreme Court’s 1973 Roe vs. Wade decision that legalized abortion nationwide. Some top contenders – including Sens. Ted Cruz and Marco Rubio – disapprove of abortions even in cases of rape and incest.

“We may very well have the most extreme Republican presidential nominee since Roe – a nominee who’s not in favor of abortion in any possible way,” said Stephanie Schriock, president of Emily’s List. The organization, which supports female candidates who back abortion rights, says it is en route to breaking its fundraising records. A similar claim is made by some anti-abortion groups.

What’s changed for this election? One factor is the increased polarization of the two major parties. Only a handful of anti-abortion Democrats and abortion-rights Republicans remain in Congress, and recent votes attempting to ban late-term abortions and halt federal funding to Planned Parenthood closely followed party lines.

Another difference: Republicans in the presidential field and in Congress seem more willing than in past campaigns to take the offensive on abortion issues. Past nominees George W. Bush, John McCain and Mitt Romney opposed abortion but were not as outspoken as some of the current Republican candidates.

“Abortion will bubble over into the general election,” said Marjorie Dannenfelser, president of the Susan B. Anthony List, which supports female candidates opposed to abortion. “If you don’t know how to handle this issue, you will be eviscerated.”

Also unfolding during the campaign will be a new investigation launched by House Republicans to examine the practices of Planned Parenthood and other abortion providers. The investigation – denounced by Democrats as a witch hunt – is among several congressional and state probes resulting from the release of undercover videos made by anti-abortion activists. They claim the videos show Planned Parenthood officials negotiating the sale of fetal tissue in violation of federal law; Planned Parenthood says the programs in question at a handful of its clinics entailed legal donations of fetal tissue.

Cruz has already passed judgment on Planned Parenthood, calling it “an ongoing criminal enterprise.”

Donald Trump has been harder to pin down on the issue. He describes himself as “pro-life” and open to defunding Planned Parenthood, while acknowledging that he held different views in the past.

Planned Parenthood’s political action fund hopes to spend more than $15 million on election-related advocacy.