Rep. Mark Kirk (R-Ill.) joined Senate Republicans for their weekly policy luncheon Tuesday, fueling speculation that he will soon formally announce his campaign for the Senate in 2010.National Republican Senatorial Committee Chairman John Cornyn (Texas) said he invited Kirk, a five-term Member who represents Chicago’s northern suburbs, to join the GOP Senators’ meeting.“We’re happy to have him. He’s considering a race, and we look forward to the possibility,— Cornyn said, adding that he expects Kirk to make an announcement “soon.—Kirk has not publicly announced his intentions for 2010, although last week he indicated to colleagues that he would soon announce his bid. Illinois Republican Party Chairman Andy McKenna issued a statement Monday vowing that he would not challenge Kirk in a primary for the Senate, giving Kirk a clear field for the seat once held by President Barack Obama and now held by embattled Sen. Roland Burris (D). Burris, appointed by former Gov. Rod Blagojevich (D), announced last week that he wouldn’t look to retain the seat in 2010.