The newspaper said Friday (http://trib.in/2e2Bg7d ) that "due to forces beyond his control, Kirk no longer can perform to the fullest the job of a U.S. senator."
Kirk spokesman Kevin Artl called it "a low-blow and cheap shot" that's "not based on fact or reality."
The newspaper endorsed Duckworth despite noting that Kirk's socially moderate and fiscally conservative positions mirror those of its editorial page.
Kirk suffered a stroke in 2012 and returned to the Senate in 2013. The newspaper said Kirk is not "as influential an advocate in Washington as he was for more than a decade."
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