There are some people out there that think Primaries should be open. In effect, they want to allow Democrats to vote on who the Republican Candidate should be, and vice-versa. I used to disagree with this idea, for several reasons. First, once you do that, there is less need/benefit/advantage to actually joining a political party. Second, some might sabotage the opposing party - for example a bunch of Democrats could all vote for a Republican they think they can beat - such as Sarah Palin that no serious person thinks can win against Obama. . Of course that might backfire if they turn around and win. Thirdly, it is the Republican's (or Democrat's) Primary, not the country's primary, why should anyone that is not a member of that party be allowed to vote? We don't let Coke vote on who's going to run Pepsi! The same goes for the other way around ( Republicans voting in a Democratic primary).
My solution is simple - give the party members extra votes and opposing members less. This gives clear advantages to joining a party, makes sabotage much more difficult, and recognizes whose primary it is. I am not saying that this should be a law, just that both parties should do this. In fact, I think that if one party would do it and the other refused, the party that took my advice would come ahead - with more 'electable' candidates.
The way I see it, a Democrat voting in a Democrat Primary should get 3 votes. An independent gets 2 votes while a member of any other political party gets 1 vote. These ratios are not set in stone - and can be altered. If you still have fear of abuse, you could start it off at 6 votes for a Democrat, 1 vote for an independent and no votes for the Republicans.
Similarly, the GOP could give the GOP members 3 (or 6 or whatever) votes, independents 2 (or whatever), and Democrats 1 vote (or whatever) etc.etc. I suspect that Obama still would have beat Clinton using this methodology. The GOP really disliked her - more than any planned attempt to sabotage her would have helped- and now they are wishing she had won. So would have McCain - despite the rhetoric both were relatively moderate candidates as opposed to the rather radical ones we are currently seeing in the GOP partisans.
But it does do three things. First, it discourages extremes. Suddenly there is some cost for going to extremes. Second, it encourages more electable candidates. It doesn't just weaken the radicals, but it empowers the main stream candidates. Isn't that a great phrase "Main Stream" it is so much better than moderate which the extremists have used as an insult. It isn't. Moderate/Main Stream means more people agree, whereas radical/extreme means LESS people believe it. Thirdly, and most important, it discourages mudslinging. If you attack the other party, as opposed to promoting your own ideas, you lose out. So the rhetoric would shift. That alone would be a major benefit. Less mud thrown makes for a better election, a more civil country.