Martin E. Sullivan, who as director of the Smithsonian’s National Portrait Gallery from 2008 to 2012 tried to push the museum past its reputation for staid and unrisky works of art and found himself at the center of a battle over self-censorship, died Feb. 25 at his home in Piney Point, Md. He was 70.

Dr. Sullivan resigned in May 2012 after a stroke. The immediate cause of death was renal failure, his daughter Bethany Sullivan said.

A museum executive for three decades, Dr. Sullivan was credited at the National Portrait Gallery with commissioning works depicting a world far beyond its traditional emphasis on presidents and first ladies. Such portraits included those of Special Olympics founder Eunice Kennedy Shriver and restaurateur Alice Waters.

In October 2010, the portrait gallery mounted “Hide/Seek: Difference and Desire in American Portraiture,” considered one of the museum’s more ambitious efforts to move beyond dignified portraits of American leaders. It was billed as “the first major museum exhibition to focus on sexual difference in the making of modern American portraiture” and included works by Jasper Johns and Andy Warhol.

The exhibition immediately drew the ire of conservative advocacy groups and House lawmakers for its inclusion of a work of video art that offended some Christians. “A Fire in My Belly,” a video created by the late David Wojnarowicz, briefly depicted a crucifix covered with ants.

Martin E. Sullivan, former director of the Smithsonian's National Portrait Gallery in Washington. (Mark Gulezian/National Portrait Gallery/Smithsonian)

Wojnarowicz, who died in 1992 of complications from AIDS, made the video in the 1980s. Its reappearance at the gallery led to an uproar by congressional leaders, including soon-to-be House Speaker John A. Boehner (R-Ohio) and Jack Kingston (R-Ga.), a member of the House Appropriations Committee. They objected to the use of taxpayer dollars for the Wojnarowicz piece.

Bill Donohue, president of the Catholic League advocacy group, told the New York Times that Wojnarowicz’s art was hate speech. “It would jump out at people if they had ants crawling all over the body of Muhammad,” he said.

By late November, Smithsonian Secretary G. Wayne Clough ordered Wojnarowicz’s art taken down, spurring a furious national debate about censorship. The incident also seemed poised to provoke a revival of the culture wars of the 1980s and 1990s over the purpose of art and, specifically, the federal funding of art.

It fell to Dr. Sullivan to explain the Portrait Gallery’s decision publicly. He called “A Fire in My Belly” a distraction from the rest of the show and added that he did not want to make the museum the target of those seeking to cut federal arts budgets.

He told the Times: “The piece, which was made in the late ’80s in Mexico, had much more to do with the reality of the suffering of the AIDS epidemic in Latin American culture, with that vivid, colorful imagery and sometimes shocking metaphors.”

Soon after the outcry, the Museum of Modern Art in New York acquired the Wojnarowicz video.

Martin Edward Sullivan was born Feb. 9, 1944, in Troy, N.Y. He was a 1965 graduate of Siena College in Loudonville, N.Y. At the University of Notre Dame, he received a master’s degree in 1970 and a doctorate in 1974, both in American history.

Early in his career, he helped administer museum grants programs at the National Endowment for the Humanities. As director from 1983 to 1990 of the New York State Museum in Albany, N.Y., he led the return of sacred belts from the museum collection to the Onondaga Nation of Indians.

For much of the 1990s, Dr. Sullivan was director of the Heard Museum of American Indian Art and History in Phoenix. From 1999 to 2008, he was chief executive of the Historic St. Mary’s City museum in Maryland, where he reportedly raised $30 million, in large part from the state, to focus on restoration and archaeology.

Dr. Sullivan served on national boards on museum standards, ethics and practices. From 1995 to 2003, he chaired the State Department’s Cultural Property Advisory Committee, which advises the U.S. government on the pillage, looting and illicit sale of antiquities.

Among other honors, he received the American Alliance of Museums’ 2014 award for distinguished service to museums.

Survivors include his wife of 32 years, Katherine Hostetter Sullivan of Piney Point; two daughters, Abigail Maslin and Bethany Sullivan, both of Washington; a stepson, James Matthew Cole of Cave Creek, Ariz.; a brother; and a grandson.