There seems to be a trend in politics for those in one party to meddle in the selection of candidates of the other party. This came to light in a major way in the 2008 Presidential primary when conservative Republicans responded to Rush Limbaugh's call to "Operation Chaos", asking GOP voters to cross over and vote against their (then) most-hated candidate, Hillary Clinton. Well they did, Barack Obama won the nomination, and guess what, he won in November.
Now, the state Democratic party seems to be trying to help State Treasurer Richard Mourdock knock off long-time incumbent Senator Richard Lugar. They think Mourdock would be an easier candidate to attack, and they are right. They have issues with Lugar being in Congress so long, and concerns about his residency, and they are right about that.
But what if Mourdock beats Lugar, then goes on to defeat Congressman Joe Donnelly in the November election? As no fan of Mourdock at all, as he wasted millions of dollars of the public's money trying to kill Chrysler, what service would it be to Indiana or the nation to elect this man?
Generally, I am in favor of the two best and strongest candidates competing in a battle of ideas and organization in a general election. This usually serves the public best, not that the result is always right. But trying to pick your opponent strikes me as a Bad Idea, bad politics, and bad for the public.
Beware of what you ask for, you might get it. And regret it.