The first rule of primary elections is that they are completely different from general elections. What it takes to win a primary is often exactly the opposite of what it takes to win a general, which is why potentially strong general election candidates are often especially weak primary candidates, and vice versa.
California Gov. Arnold Schwarzenegger may be the most obvious case in point: Republican primary voters would never have picked him over a more conservative choice. He initially won in an "open" recall ballot, which is one reason he is sponsoring a referendum on next month's California primary ballot to make all primaries open.
General election voters might not have cared so much that former President George W. Bush was Sen. Arlen Specter's best friend until a year ago. But Neil Oxman's brilliant ad for Rep. Joe Sestak, D-Pa., reminding Democratic Party members that Specter only joined the party to save his job, may go down as the best ad of this season.
Add to that the fact that any Democratic woman over 40 will never forget Specter's merciless 1991 grilling of Anita Hill (to save his seat in 1992), and you have a recipe for primary disaster. Specter might have been able to beat a Republican in a general election, but he could not beat a real Democrat in a Democratic primary.
Some commentators may try to play primary day as a referendum on the Obama presidency and the Democratic Congress, but that hardly explains ophthalmologist Rand Paul's victory in Kentucky. Running against the man handpicked by Minority Leader and Kentucky Sen. Mitch McConnell, and endorsed by no less a Republican hero than former Vice President Dick Cheney, Dr. Paul's tea party steamrolled across the state.
Of course, the tea party movement had, and has, the power to influence elections. Even if they number "only" 18 percent, as some polls suggest, that's a major movement in Republican primaries. But 18 percent is a lot less in a general election, where 100 percent of the electorate is eligible to vote.
Whether the tea party-backed Paul is the strongest Republican to run in November remains to be seen. My guess is that he is not.
If there is a theme coming out of this week's primaries, it is the familiar one — that contested primaries favor insurgent candidacies.
Blanche Lincoln is in trouble from the left in the primary, but both she and her Democratic rival are trailing their conservative opponent in the general election match-up. Lincoln has to walk the fine line between going far enough to the left to win 50 percent of Democrats without going so far left that she ultimately loses 50 percent of voters.
Politics is a tricky business.
Here in California, the fun is two weeks away. In the Republican gubernatorial primary, frontrunner Meg Whitman, former eBay CEO, has seen her lead decline amid very tough attacks against her conservative credentials by her rivals. Democrats could not be more relieved.
At worst, Whitman will be severely scarred. At best, California state Attorney General Jerry Brown will face an opponent who is way to the right of most California voters.
So, too, for Sen. Barbara Boxer, D-Calif., whose Republican opponents are outdoing each other to try to appeal to a minority of California voters, potentially at great cost to their chances against Boxer.
Primaries have two often inconsistent purposes. One is for party activists to define their party. The other is to pick candidates who can win.
Tuesday's contests were much more about the former than the latter: tests of ideology and loyalty at the possible expense of pragmatism.
It remains to be seen whether California will continue that trend. But I wouldn't take it as a judgment, one way or the other, on the likely outcome of the battle for control of Congress in November.
© Creators Syndicate Inc.