Kirk's campaign manager, Kevin Artl, told The Daily Herald newspaper on Thursday that the senator would be focusing his efforts on his re-election bid against Democratic Rep. Tammy Duckworth rather than joining his fellow GOP lawmakers in Cleveland.
"Senator Kirk has his own re-election to win, so he will be working hard toward that goal, not going to the Republican convention in Ohio," Artl said.
Kirk isn't the only lawmaker hesitating to attend what could be a battle royale in Cleveland ahead of a tough battle to hold on to his own seat in November. Sen. Kelly Ayotte (R-NH) told CNN it was "unlikely" she would attend the convention, and Sen. Richard Burr (R-NC) also expressed hesitation.
Florida Gov. Jeb Bush (R) has also said he will not attend.
Kirk also made headlines recently for being the first Republican senator to meet with President Obama's Supreme Court nominee, Merrick Garland.