National security and a fitful economy are debated constantly on the campaign trail these days, but an issue barely mentioned by the major parties — abortion — is proving to be among the most divisive in several Senate races that could affect the future of abortion rights.

With control of the Senate up for grabs Nov. 5, both sides in the abortion debate consider the stakes momentous. A return to Republican control, they agree, could result in the next Supreme Court vacancy going to a justice who would tilt the court toward more restrictions on abortion.

"For Americans who are pro-choice, it's a very scary thought," said Mary Jane Gallagher, executive vice president of the National Abortion and Reproductive Rights Action League (news - web sites), which has spent $3.5 million on campaign ads in recent weeks.

"If we lose the Senate, we're going to lose the Supreme Court, and then a woman's right to choose is clearly at risk," Gallagher said.Ken Connor, president of the conservative Family Research Council, said NARAL and its allies have succeeded in raising money by "creating an atmosphere of hysteria."

Yet he shared NARAL's view about the election's high stakes.

"The pro-abortion lobby is concerned that the right to abortion is in jeopardy, and it may well be — if President Bush (news - web sites) succeeds in appointing judges who interpret the constitution rather than rewrite it," Connor said.

Connor envisions a Republican-controlled Senate confirming a Bush nominee to the Supreme Court who would then help overturn the 1973 Roe v. Wade (news - web sites) ruling that legalized abortion nationally. That would return the matter to state legislatures to make their own decisions.

With both major parties wooing middle-of-the-road voters on economic and security matters, abortion is among a relatively small group of issues producing stark contrasts between candidates in pivotal races.

Among the neck-and-neck Senate contests, those in New Hampshire, Colorado and Missouri pit a Democrat who supports abortion rights against a Republican who opposes abortion in most or all cases.

The same pattern holds true in several other states where one candidate has an edge but the race is still considered competitive — including Georgia, Iowa, North Carolina, Oregon and Texas.

Sen. Paul Wellstone, the Minnesota Democrat killed in a plane crash last week, was one of the abortion rights movement's staunchest supporters. His replacement, Walter Mondale, also backs abortion rights, while the Republican candidate, Norm Coleman, quit the Democratic Party partly because he opposes abortion.

Of the Democrats in close Senate races, Arkansas Attorney General Mark Pryor has probably struggled most with the issue. He described himself as "pro-choice" in 1998, but said this year he won't accept any label because abortion is complex. Sen. Tim Hutchinson (news, bio, voting record), the Republican incumbent, said Pryor is taking "four sides on a two-sided issue."

In New Jersey, Republican candidate Douglas Forrester also has struggled to define his stance. He describes himself as supporting abortion rights, but has drawn fire from groups like NARAL because he opposes public funding of abortions.

The partisan split on abortion supersedes gender. In New Hampshire and Missouri, female Democrats who support abortion rights are opposing male Republicans who don't. In North Carolina, a man — Erskine Bowles — is carrying the Democrats' abortion-rights banner against Republican Elizabeth Dole (news - web sites), who opposes most abortions.

Tovah Ravitz-Meehan, spokeswoman for the Democratic Senatorial Campaign Committee, said abortion is more problematic for the Republicans than the Democrats because the GOP seeks to woo the Christian right and suburban moderates simultaneously.

Dan Allen, spokesman for the National Republican Senatorial Committee, said GOP strategists found the best approach was to raise the issue in specific races in conservative states. Neither the committee nor the White House is highlighting the issue nationally.

Connor said the strategy is flawed, and urged the GOP to be more vocal in opposing abortion.

"The Republican smart guys say there's more political capital to be gained by muddling your positions on these social issues," he said. "I think voters are looking for plain talk and principled leadership."

Though the stakes are highest in the Senate races, abortion also has surfaced in races for governor and the U.S. House.In New Mexico, the Roman Catholic Archdiocese of Santa Fe ventured into the gubernatorial campaign, circulating fliers about the candidates' stands on abortion. The fliers, published by Right to Life of New Mexico, criticized Democrat Bill Richardson for supporting abortion rights, while noting that Republican John Sanchez has a "100 percent pro-life voting record."

By David Cary