Republican Sens. Charles Grassley and Mark Kirk said they will block the confirmation of Richard Berner, a former economist at Morgan Stanley, as head of the new Office of Financial Research. Grassley and Kirk said they are upset about the way Treasury Secretary Timothy Geithner handled the London Interbank Offered Rate issue. "During your tenure as Treasury secretary, nothing has been done to diminish use of this flawed index in U.S. financial markets," the senators said in a letter to Geithner.