At CNN, "In statement, Lugar defends campaign while criticizing partisan environment" (via Memeorandum):
From time to time during the last two years I heard from well-meaning individuals who suggested that I ought to consider running as an independent. My response was always the same: I am a Republican now and always have been. I have no desire to run as anything else. All my life, I have believed in the Republican principles of small government, low taxes, a strong national defense, free enterprise, and trade expansion. According to Congressional Quarterly vote studies, I supported President Reagan more often than any other Senator. I want to see a Republican elected President, and I want to see a Republican majority in the Congress. I hope my opponent wins in November to help give my friend Mitch McConnell a majority.Sorry, Dick, but the times have passed you by.
If Mr. Mourdock is elected, I want him to be a good Senator. But that will require him to revise his stated goal of bringing more partisanship to Washington. He and I share many positions, but his embrace of an unrelenting partisan mindset is irreconcilable with my philosophy of governance and my experience of what brings results for Hoosiers in the Senate. In effect, what he has promised in this campaign is reflexive votes for a rejectionist orthodoxy and rigid opposition to the actions and proposals of the other party. His answer to the inevitable roadblocks he will encounter in Congress is merely to campaign for more Republicans who embrace the same partisan outlook. He has pledged his support to groups whose prime mission is to cleanse the Republican party of those who stray from orthodoxy as they see it.
This is not conducive to problem solving and governance.
And in case you missed it, there's been a grassroots tea party revolt raging for the past three years. Have a nice retirement.