(CHICAGO) Republican U.S. Senator Mark Kirk hopes that walking up 37 floors of the Willis Tower in Chicago will send a message that he’s physically capable to handle another term in office.

Kirk is being challenged by Democratic U.S. Rep. Tammy Duckworth and one of the issues that has emerged is whether Kirk’s 2012 stroke compromised his ability to do the job.

Kirk has released a letter from his physician that says he’s made a full cognitive recovery and before Sunday’s climb he said he hoped the climb would demonstrate his physical ability to serve a second term in the Senate.

Kirk completed the climb along with others participating in SkyRise Chicago, an event that benefits the Rehabilitation Institute of Chicago. Kirk was treated at the institute after his stroke.

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