I stand on one basic principle in this regard. I have taken exactly the same oath as Mr. Lott - and one of the duties is to "protect and defend the Constitution of the United States."
The word "protect" has an awesome meaning in this context. It requires the oath-taker to take care the intent (not just the words, that is not sufficient) of the Constitution be carried out in the name of the American people.
Mr. Lott has found it suitable on at least one occassion to bend the meaning of that oath (he stretched it a bit with the "trial" of UOx42, but it can be argued it was still within Constitutional confines, so I'm not talking about that). That occassion was the seating of the window Carnahan as a Senator from Missouri - a position she had no business assuming as the late Governor could not have been presented, legally, on the ballot. (Though I do have to admit I still sort of like the fact the Criminal Party did support the equal opportunity cause in that regard by electing a living-impaired individual.)
At that point, it was clear Mr. Lott had a greater concern about getting along with the Criminal Party than with "protect[ing] and defend[ing]" the Constitution of the United States of America.
This is not a quality of a leader, IMO.