[Vigilanteman]

Only Republicans resign Senate seats to run for president (Barry Goldwater in 1964, Bob Dole in 1996). Democrats always cling to power and only if they are successful in achieving higher office will they resign (JFK-LBJ in 1960). If they don't win, they still have their senate seat (e.g. Lieberman in 2000). "Serving their constituents" is only an excuse for election in the first place. It is not, and never has been, a reason to resign to run for higher office.

One reason Little Tommy Daschle declined to run is because the South Dakota legislature passed a law forbidding the listing of the same candidate for more than one office. It would be the ultimate poetic justice if he loses his senate seat anyway.

[Publius]

Only Republicans resign Senate seats to run for president (Barry Goldwater in 1964, Bob Dole in 1996).

Goldwater did not resign his Senate seat. He chose not to run for re-election in 1964. Republican Paul Fannin won Goldwater's seat.

Goldwater returned to the Senate in 1968 when he defeated retiring Sen. Carl Hayden's chief aide, Ray Ellis, who ran to succeed Hayden.

For the Republican convention in 1968, Goldwater piloted his private jet into town, made a speech and flew back to Arizona to campaign. His "People Power" speech at the 1968 Republican Convention was the best speech of his entire career.