Mark Kirk was born in 1959 in Champaign, Illinois, and studied at Blackburn College, the Autonomous University of Mexico and Cornell before earning a master’s from the London School of Economics and a Georgetown law degree. He was chief of staff to Congressman John Porter, worked at the World Bank and Baker McKenzie, and in 2000 won Porter’s 10th District seat, where he chaired the centrist Tuesday Group. A Navy Reserve intelligence officer from 1989 to 2013, he was recalled during the 1999 NATO bombing of Yugoslavia, but in his 2010 race for Barack Obama’s former Senate seat he admitted embellishing his record, including an intelligence officer of the year award that actually went to his unit. He apologized and narrowly beat Alexi Giannoulias.

In the Senate he took over the candy desk, was ranked the sixth most bipartisan senator by the Lugar Center, supported same sex marriage and met with Supreme Court nominee Merrick Garland in 2016. In January 2012, at 52, he suffered an ischemic stroke that required a craniectomy at Northwestern Memorial Hospital. That November he climbed 37 floors of the Willis Tower, and in January 2013 he walked up the Capitol steps on Vice President Joe Biden’s arm. In an October 2016 debate he answered Tammy Duckworth’s mention of her family’s military history by saying he had forgotten her parents came from Thailand to serve George Washington. The Human Rights Campaign withdrew its endorsement, a first for the group, and he lost 55 to 40 percent.

• He claimed on the House floor that Iraqi air defenses fired at him, then admitted there was no record of it.
• The Pentagon counseled him twice for mixing politics with duty, including tweeting about Rod Blagojevich’s arrest while deployed to Afghanistan.
• He was the only Republican senator with an F grade from the NRA and the only one to vote for the 2013 assault weapons ban.
• He withdrew his support for Donald Trump in 2016 and said he would write in David Petraeus.
• He pushed to protect the Great Lakes from Asian carp and sewage dumping.