Longtime Republican Rep. Frank Wolf of Northern Virginia said Tuesday he won't seek an 18th term next year, saying he wants to devote more time working on "human rights and religious freedom" issues.

"As a follower of Jesus, I am called to work for justice and reconciliation, and to be an advocate for those who cannot speak for themselves," the Republican said. "I plan to focus my future work on human rights and religious freedom — both domestic and international — as well as matters of the culture, and the American family."

Wolf, 74, said his passions for those issues have been influenced by the work of President Reagan, former Reps. Jack Kemp, a Republican, and Tony Hall, a Democrat, former Special Counsel to President Nixon Charles Colson, and William Wilberforce, an 18th- and 19th- century British politician and anti-slave-trade activist.

"It has been an honor to serve the people of Northern Virginia and the Shenandoah Valley," Wolf said. "I want to thank the many excellent former and current members of my staff who have helped me serve the people of the 10th District. I am also grateful to my wife, Carolyn, and my family, who have faithfully stood by me all these many years.”

Wolf, the dean of the Virginia congressional delegation, was first elected to Congress in 1980. He is a member of the powerful House Appropriations Committee and co-chairman of the Tom Lantos Human Rights Commission, a bipartisan congressional caucus.

Wolf, who sits on the House Appropriations Committee, was first elected in 1980. Since then, his district has trended toward the political center — which could set up a close race to replace him.

Wolf's district narrowly supported Romney in 2012, 50 percent to 49 percent, and went for Ken Cuccinelli, a Republican, in the Virginia gubernatorial race last month by the slim margin of 48 percent to 47 percent. The district includes Loudoun county and parts of Fairfax and Prince William counties in the Northern Virginia suburbs of Washington, D.C.

Democratic Sen. Mark Warner, a fellow Virginian, called Wolf a "true friend and a great partner."

"Frank has also been a passionate advocate and reliable ally in my ongoing efforts to find common ground on issues surrounding our nation’s deficits and debt," Warner said.

"Congressman Wolf’s dedication in over 17 terms in Congress," Warner said, "and his exceptionally high level of service to the constituents he proudly represents in Virginia’s 10th District, will remain a model for all of us who serve."

Examiner Political Correspondent Rebecca Berg contributed to this report.