It is critical the Republican nominee emerge from this primary campaign un-bloodied, so that he or she can make the case against President Obama from a position of strength.

For these reasons I have refrained from launching attacks on my Republican opponents, though I have reserved the right to respond when my record has been distorted. On Monday this occurred when Governor Romney and I engaged in what in diplomatic circles is called “a frank exchange” over our respective records in the private sector. That same day, however, Mr. Romney announced, “I’m not going to say outrageous things that can be used to hang [a GOP opponent] down the road.” I agree wholeheartedly with this statement. So let us hope that from this point forward we can devote our energies to real issues, such as discussing our plans for our nation’s economic recovery and helping to create millions of new jobs for the American people.

I also want to reiterate to each of you what I have said from the beginning of our campaign, and most recently last Saturday in Iowa: We will run a positive campaign focused on our country’s future. We will not be running any negative advertising. With Ronald Reagan’s eleventh commandment in mind, we will ask our supporters not to contribute to any so-called SuperPAC that runs negative ads against any other Republican contender and we will discourage ad hominem attacks on our fellow Republicans.