He was appointed by Governor Ann Richards in 1993 to the U.S. Senate to fill the vacancy caused by the resignation of four-term incumbent and 1988 Democratic Vice Presidential nominee Lloyd Bentsen, who became Secretary of the Treasury in President Clinton's cabinet. He served from January 21, 1993 until June 14, 1993. He lost the June 1993 special election runoff for the remainder of the term ending January 3, 1995 by a 2-to-1 margin to the popular Texas State Treasurer, Republican Kay Bailey Hutchison. In 2010, Krueger's campaign was named by the same "Houston Chronicle" article as the single worst in Texas' modern political history. Reasons cited for the defeat included Krueger's flip-flopping over don't ask, don't tell and also Bill Clinton's proposed BTU tax, which was unpopular in Texas.