Mark Kirk (Scott Ferrell/CQ)

Illinois Rep. Mark Steven Kirk will run for the Senate next year — a sign that the Republican Party will seriously compete in a Democratic-leaning state for the seat formerly held by President Obama.

A GOP source confirmed Wednesday that Kirk plans to seek the Senate seat of interim Democrat Roland W. Burris . Asked about his political plans by my CQ colleague Jonathan Allen, Kirk declined comment but allowed that, “I’m living on my phone right now.”  

It’s common for a prospective candidate to give political activists and major donors a heads-up about an upcoming campaign before it is publicly announced.