Opponents of the open primary believe that the open primary leaves the party nominations vulnerable to manipulation and dilution. First, one party could organize its voters to vote in the other party's primary and choose the candidate that they most agree with or that they think their party could most easily defeat.
Secondly, in the open primary moderates and independent voters can vote in either party. This occurrence may dilute the vote of a particular party and lead to a nominee who does not represent the views of his particular party.
For example, in the 2008 presidential primaries, exit polls say John McCain failed to win a single race among Republican voters, up to Super Tuesday, yet during that same period he went from also-ran to front runner, because most non-Republicans who crossed over voted for him.
In New Hampshire, Mitt Romney won among registered Republicans, but John McCain won overall . Likewise, in South Carolina, Mike Huckabee won among self-identified Republicans, but John McCain won the state .
Similarly, some Republican advocates called for Republicans to cross over and vote in the Democratic race, to help Hillary Clinton win, on the premise that Obama had a better chance of beating their candidate. The Rush Limbaugh Show's "Operation Chaos" is the best known of these movements.
States with an open presidential primary
If you live in one of these States and support The Prez, vote in the primary for the weakest dumbest Republican... And then Re-elect Obama in 2012.
http://nubiannewyorkers.blogspot.com/