Ellen McCormack, an antiabortion activist who drew attention to her cause and stirred controversy over campaign finance rules when she ran for president in 1976 and 1980, died March 27 at an assisted living facility in Avon, Conn. She was 84 and had congestive heart failure.

Mrs. McCormack, a Long Island, N.Y., homemaker and grandmother, became the first female presidential candidate to qualify for Secret Service protection and federal campaign subsidies.

She had never held a political office when she launched her first drive for the White House, three years after the Supreme Court recognized a woman’s right to an abortion with its landmark Roe v. Wade decision.

Although she sometimes spoke about busing, welfare and conflict in the Middle East, she said her sole aim was to force candidates and voters to confront the issue of abortion.

“I stand for the rights of the unborn,” she told the New York Times. “I’m basically a one-issue candidate.”

The sole Democratic presidential candidate to advocate for a constitutional ban on abortion, Mrs. McCormack won more than 200,000 votes in 18 primaries.

She netted three delegates to the national convention, where her name was placed in nomination with Rep. Morris K. Udall of Arizona, Gov. Jerry Brown of California and Jimmy Carter.

Mrs. McCormack “played a major role in the rise of the pro-life movement,” Phyllis Schlafly, a prominent antiabortionist, wrote in 2007. “After her campaigns for president, politicians who had been timid about saying they opposed abortion and Roe v. Wade came out of the woodwork and confidently stated their views.”

Mrs. McCormack’s presidential run was a grass-roots affair run by a group she co-founded, the Pro-Life Political Action Committee.

Her campaign triggered dismay in some quarters when it raised $5,000 in each of 20 states, thus qualifying for public campaign funds. Over the course of the race, she raised about $250,000, an amount that was matched dollar for dollar by the federal government. The money primarily paid for antiabortion ads that ran during prime time on TV and radio.

Critics said Mrs. McCormack was unfairly taking advantage of the campaign finance rules, using taxpayer money to promote her single cause when she had no chance of winning the presidency. Mrs. McCormack disagreed.

“The professional politicians are making a great many mistakes,” she told Newsweek in 1976. “I don’t think I should be disqualified just because I haven’t been making those mistakes for the past 20 years.”

As the controversy simmered, the right-wing John Birch Society and the National Right to Work Committee, which opposes compulsory union membership, announced their own presidential candidates and began preparing requests for federal funding.

Congress took action in March 1976, guarding federal funds by eliminating from eligibility any candidates who failed to win at least 10 percent of the vote in two consecutive primaries.

After her loss in 1976, Mrs. McCormack went on to co-found the national Right to Life Party and in 1978 ran under its banner for lieutenant governor of New York. She and her running partner, another Long Island mother and activist, Mary Jane Tobin, won 120,000 votes.

In 1980, Mrs. McCormack ran again for the White House as an independent, but the antiabortion movement largely threw its support to Ronald Reagan.

Eleanor Rose Cullen was born Sept. 15, 1926, in New York. She went by her nickname, Ellen, for most of her life.

Her husband of 44 years, Francis John McCormack, was a New York police officer. He died in 1993.

Survivors include four children, Kathleen McCormack-Batterson of Farmington, Conn., Anne McCormack of Sag Harbor, N.Y., Ellen Stapleton of Holbrook, N.Y., and John McCormack of Yardley, Pa.; two sisters; 11 grandchildren; and four great-grandchildren.

Mrs. McCormack, a Roman Catholic, first protested against abortion in Albany in 1969, the year before New York made the procedure legal.

“Some people called it a ‘fetus,’ ” she told the Times. “I was convinced it was a human life being taken. It was a baby. It was a terrible thing to do.”

She wrote a weekly syndicated column — “Who Speaks for the Unborn?” — that ran in hundreds of Catholic publications. She also founded an antiabortion organization that gave slide shows in schools.

Mrs. McCormack first stepped into electoral politics in 1974 as an aide to third-party antiabortion candidate Barbara Keating, who ran from New York for the U.S. Senate.

Later, during her own bids for office, Mrs. McCormack shunned the usual trappings of a national campaign. She had no press secretary, booked cheap motels and reserved at least a day a week for chores at home. Nevertheless, she seemed comfortable on the stump.

“We who oppose abortion may lack the power of the pro-abortionists,” she told a 1976 gathering in Vermont. “But we will make up for it in dedication and sacrifice, and we will overcome. We have the same spirit and vision the abolitionists did.”