Vernon J. Ehlers, a physicist and longtime Republican congressman from Michigan whose scientific background led him to embrace political positions at odds with those of his party, died on Aug. 15 at his home in Grand Rapids, Mich. He was 83.

Rick Treur, Dr. Ehlers’s former campaign manager, said the cause was Alzheimer’s disease.

A nuclear physicist and college professor before he entered politics, Dr. Ehlers was elected to Michigan’s third district in 1993 and retired in 2011. Scientists were, and remain, a rarity in elected politics in America; he said he was the first research physicist ever elected to Congress.

Dr. Ehlers was part of the wave of Republicans that took control of the House and Senate after the 1994 elections, leaving President Bill Clinton, a Democrat, without a majority in Congress for the rest of his presidency.

Dr. Ehlers was a fiscal conservative who worked to enact Speaker Newt Gingrich’s policy agenda, known as the “Contract with America” — an ambitious set of proposals that often led to compromises with the executive branch. He stood with his party on key issues like balancing the budget, limiting the size of the federal government and repealing a ban on assault weapons.