Argument: Open primaries allow tactical manipulation
James Frye. "Why open primaries are a really bad idea." Liberaland. June 9th, 2010: "The open primary is also an invitation for one party to see to it that the weakest possible candidate of the other party wins to ensure that their real candidate has a better chance in the general election. This appears to have been what happened in the case of Mr. Greene’s Democratic nomination ‘victory’ in South Carolina. Sneaky? Yes, but totally legal and the SC Democrats would have done the same to the Republicans if they could."
State Sen. Ken Cuccinelli II (R-Fairfax) said in opposition to Open Primaries: "Why on Earth would anyone think that my opponents have any right to pick my nominee?. The Washington Redskins don't let the Dallas Cowboys in their huddle when they're calling plays."
"Open primaries are an open invitation for political mischief." Telegraph. August 16th, 2009: "We need to determine the consequences of allowing a party's candidate to be chosen by supporters of other parties and none. As a Tory, if I were given the opportunity of voting for a prospective Labour candidate, I would have the choice of two strategies: to vote for a candidate whose opinions were closest to my own, as an insurance in case my party's candidate were to lose, or to choose an activist whose unreconstructed Marxism would not appeal to the majority.
If open primaries were used to challenge a sitting member who wished to seek re-election, supporters of opposing parties would welcome the opportunity to cause disruption by voting for anyone but the sitting member."