If I remember correctly, the only reason Tower won was because then the Texas Democratic party was split between liberal and conservative wings. Typically the primaries would have a liberal vs. conservative, and whoever won was considered a shoo-in in the general election. In that case, a conservative Democrat won the primary, and thus many on the liberal wing led a campaign to vote for Tower in the general, with the theory being they could easily beat him later. Obviously that didn't work, but his initial victory was always a bit of a fluke.
If I recall, it was the other way around, as conservative Democrat Coke Stevens endorsed Tower giving him inroads with the Democratic voters. I think it is a mistake to say Tower's victory was a fluke, as his election came as a result of years of work, planning, and campaigning. He basically built the Texas GOP where there had effctively been none before. That is my outlook on that.
The CA GOP is in bad shape, but I do not buy the hype that a conservative cannot win statewide. Tom McClintock has ran two statewide campaigns, coming within a hair of victory the second time around, and he very well could become Lt. Governor this November. McClintock is the California Conservative's greatest hope for some level of high profile success.