America's Best Senators Those who do, and don't, make a difference in the U.S. Senate The Best Senators Thad Cochran Kent Conrad Dick Durbin Ted Kennedy Jon Kyl Carl Levin Richard Lugar John McCain Olympia J. Snowe Arlen Specter The Worst Senators Daniel Akaka Wayne Allard Jim Bunning Conrad Burns Mark Dayton From the TIME Archive Nov. 5, 1979 The Kennedy Challenge More than a quarter century ago, TIME covered the presidential campaign of Senator Ted Kennedy, "the last of the Kennedy brothers, the youngest, the most vulnerable, the most thoroughly political"

When he was elected in 2000, Minnesota Democrat Mark Dayton seemed well prepared, having worked as an aide to Walter Mondale in the 1970s. But he has exhibited erratic behavior since then: in October 2004 he shut down his office for almost a month, citing an unspecified terrorist threat. The 99 other Senators had access to the same intelligence and kept their offices open, even while Dayton went on television to tell his constituents not to visit the Capitol. In February Dayton, 59, made another notable blunder. The Mayo Clinic, which is in Rochester, Minn., was opposed to a South Dakota — based company's plan to expand its railroads into Rochester because it would mean dozens of trains passing by the clinic each day. Dayton told FORTUNE magazine the Mayo Clinic is "worth a hell of a lot more than the whole state of South Dakota." He later apologized for the remark.

Inside the Senate, Dayton has passed few bills partly because some are too liberal for the Republican-controlled body, including one that would have created a Department of Peace and Nonviolence. He has confounded his colleagues by complaining about basic facts of the job, such as his limited power in a chamber where authority derives from seniority. He announced early last year that he wouldn't seek re-election.