Paul Findley, a moderate Republican congressman from Illinois who sought to limit presidents’ power to wage war and pressed the United States government to engage with the Arab world, died on Friday in Jacksonville, Ill. He was 98.

The cause was complications of congestive heart failure, his son, Craig, said.

Mr. Findley spent 22 years in Congress. When first elected in 1960 he promised to fight “creeping socialism,” but his views soon moderated and occasionally veered to the liberal side, making him part of a breed of Republicans more common then and almost nonexistent today.

He supported civil rights and, with the blessing of the Republican leadership, named the first black person in the 20th century — 15-year-old Frank Mitchell of Springfield — to the position of page in the House of Representatives.

Mr. Findley was an early critic of the Vietnam War and in 1973 helped write the War Powers Resolution, better known as the War Powers Act, which requires presidents to notify Congress within 48 hours if they send troops into combat. It also limits the time those troops can remain deployed without congressional authorization.

Mr. Findley was also known for his vocal advocacy of involvement with the Arab world, including Yasir Arafat and the Palestine Liberation Organization, which had been designated a terrorist group by the United States.

He became convinced that the influential pro-Israel lobby known as AIPAC, the American Israel Public Affairs Committee, had a stranglehold on American politicians that prevented the establishment of a Palestinian state and prevented rational dealings with Arab leaders in general.

Mr. Findley detailed his own immersion in the Middle East in his book “They Dare to Speak Out,” published in 1985 and reissued in 1989 with the subtitle “People and Institutions Confront Israel’s Lobby.”

His involvement in the region began in 1973 when a constituent asked for his help in freeing her son from prison in what was then the country of South Yemen.

That request, he said, changed his life. As he became more sympathetic to Arabs, he spoke out about his frustrations with the United States government’s overwhelmingly pro-Israel posture, though he voted regularly for aid to Israel.

“Thanks to a flow of hostile dollars from both coasts and nearby Chicago, I became ‘the number one enemy of Israel’ and my re-election campaign the principal target of Israel’s lobby,” he wrote in his book.

He won that year, but the same forces came back at him in 1982. Both races were the most expensive congressional campaigns in Illinois history up to that time.

In 1982, he lost by less than 1 percent of the vote. The winner was Dick Durbin, a Democrat and now the senior senator from Illinois.

Mr. Findley wrote that shortly after the election, Thomas A. Dine, Aipac’s executive director, took credit for the win. “This is a case where the Jewish lobby made a difference,” he quoted Mr. Dine as saying to a Jewish gathering in Texas. “We beat the odds and defeated Findley.” He said Mr. Dine later estimated that $685,000 of the $750,000 raised by Mr. Durbin had come from Jews.

Paul Augustus Findley was born on June 23, 1921, in his parents’ home in Jacksonville, in central Illinois. His father, Joseph, managed the Y.M.C.A. in Jacksonville and later became an insurance agent; his mother, Florence (Nichols) Findley, managed the cafeteria at Jacksonville High School, where, during the Depression, she made sure that even students who could not pay received a meal.

Mr. Findley attended Illinois College in Jacksonville and graduated Phi Beta Kappa in 1943. He joined the Navy in World War II and was a lieutenant stationed on the island of Guam when he met Lucille Gemme, who was also a lieutenant. She was a flight nurse whose job was to bring wounded soldiers from the battlefield back to Guam. They were married in 1946.

His wife died in 2011. In addition to their son, he is survived by their daughter, Diane Findley McLaughlin; a sister, Barbara Stuart; four grandchildren; and four great-grandchildren.

After the war, Mr. Findley started out as a journalist in Washington, then moved back to Illinois, where he became president and publisher of The Pike Press, a weekly newspaper in Pittsfield, just west of Jacksonville. He appointed someone else to run the paper while he was in Congress and later sold it.

After he lost re-election in 1982, he and his wife stayed in Washington for a time before moving back to Jacksonville, where he wrote books and lectured.

“They wanted to live in a community where they knew everyone and everyone knew them,” Andrew Findley, a grandson, told The Jacksonville Journal-Courier. “He wanted to be able to know his neighbors, to say ‘Hi’ to people on the streets. And, over the last 40 years, that’s precisely what he’s done.”