Lamar Alexander's nomination to be education secretary cleared the Senate Labor and Education Committee on Wednesday, but several Democratic senators expressed reservations about how he went from middle class to millionaire in 12 years.

The vote was 16-0 with one Democrat, Sen. Tom Harkin of Iowa, voting present. The full Senate will probably approve Alexander's nomination Thursday.The committee, headed by Sen. Edward M. Kennedy, D-Mass., spent several weeks investigating Alexander's financial holdings. Questions had been raised about his portfolio; his net worth rose from $151,000 in 1978 to about $3 million last year.

"He's made some fast bucks," Harkin said. "We ought to make him secretary of the Treasury and help retire the deficit. He knows how to make money."

Sen. Orrin Hatch, R-Utah, ranking Republican on the committee, defended Alexander and said that "while we

might all envy him, there's nothing wrong with his making money."

Sen. Barbara A. Mikulski, D-Md., said that she was concerned about some of Alexander's financial dealings but that a more important issue was "who in the heck is concerned about the kids."

Alexander, a popular two-term governor from 1978 to 1986, pushed an innovative teacher merit plan through the predominantly Democratic General Assembly and served as president of the University of Tennessee system after leaving office. He and his wife, Leslee, made a number of profitable investments over that period; the committee apparently found nothing illegal in it.

Kennedy, although finding no evidence of any violation of law, said: "Gov. Alexander was creating the appearance of a conflict of interest and the appearance of using his high public office for the private financial benefit of himself and his family."