Before becoming the second Republican from Texas to be elected to the Senate since Reconstruction, Rep. Phil Gramm (R-Tex.), 42, was best known as the sponsor of President Reagan's tax policy in the House -- while he was still a Democrat.

Gramm came to Washington a Democrat in 1978. After embracing the president's economic programs, he was booted off the powerful House Budget Committee, resigned from Congress in January 1983, and announced he would seek reelection as a Republican.

Gramm's predecessor, retiring Sen. John G. Tower -- the only other Republican senator from Texas since Reconstruction -- observed shortly after Gramm became a Republican: "He was philosophically and fundamentally a Republican before he switched, so that's all the same."

After winning a special election, he returned to the Budget Committee to a seat his Republican colleagues had saved for him.

Born at Fort Benning, Ga., the son of an Army officer, Gramm majored in physics at the University of Georgia.

He took a graduate degree in economics and went on to become an economics professor at Texas A&M. Representing a Democratic, largely rural district in the House, he described himself during the campaign as "kind of a redneck."

Gramm is known in Congress as an unyielding supporter of Reagan's programs. He seldom ventured three paragraphs into a stump speech before getting to the phrase, "Ronald Reagan and I . . ."

He supports reduced federal spending and a balanced budget. David A. Stockman, director of the Office of Management and Budget, described him as "one of the smartest guys in Congress when it comes to understanding the budget; he understands it better than anybody."

Gramm is married and the father of two sons. His wife, Wendy, is an economist, formerly with the Federal Trade Commission.