The super PAC supporting Republican Senate Leader Mitch McConnell has once again filed a campaign finance report showing no donations from Kentuckians.Founded by former McConnell campaign aide Scott Jennings, Kentuckians for Strong Leadership reported Wednesday it had raised just over $423,700 in the past three months.Unlike a candidate's campaign, federal rules allow super PACs to raise an unlimited amount of money from individuals.FEC records show hefty contributions sent to Kentuckians for Strong Leadership, mostly from business leaders and CEOs spread across the country.Among the top donors for this period are Sam Fox, chairman and CEO of the St. Louis-based The Harbour Group. Fox gave $100,000.Another big giver is Michael Aronstein, president of the New York-based Market Field Asset Management, who contributed $50,000.Other donors over the past three months had given to Kentuckians for Strong Leadership previously.For instance, John Childs is chairman and CEO of J.W. Childs Associates, a Massachusetts-based private equity firm. He donated $40,000 to the super PAC on May 9 after giving the super PAC $250,000 last year.Another donor, Ed Bosarge, a Texas oil executive, gave a relatively small contribution of $25,000 on June 16, compared to the $150,000 he gave to the super PAC last year.Kentuckians for Strong Leadership has raised about $3.7 million since Jennings formedthe group in April 2013.Just $172,000 comes from donors with Kentucky addresses, according to the super PAC's receipts.Jennings said in an email response to questions that the Senate election is a national race and "liberal supporters of Barack Obama and Elizabeth Warren are pouring money" into the state."We serve as a firewall against this national liberal onslaught," Jennings said. "McConnell is a principled conservative leader that has Kentucky’s best interests at heart. If Grimes wins, Harry Reid and Barack Obama are empowered. If McConnell wins, Kentucky is empowered. It’s a simple choice."Since its launching, Kentuckians for Strong Leadership has run some of this year's more blistering and effective attacks against McConnell’s challenger, Democrat Alison Lundergan Grimes.The ads often link Grimes’ position on issues to the agenda of President Obama and national Democrats, and to liberal donors.In response to these ads, the Grimes campaign has challenged McConnell to sign a pledge asking outside groups to stay out of the race.Pro-Grimes super PACs are running ads attacking McConnell in the race, such as Senate Majority Fund.One such Democratic-leaning group called We Are Kentucky with pro-union support failed to show any in-state donors in the first quarter. The group filed its campaign finance reports late Tuesday.We Are Kentucky showed it has raised just $50,000 over the past three months, including a $10,000 donation from an Elizabeth Goth of Lexington. The super PAC's report shows they have just over $83,000 in cash on hand.An earlier version of this story misstated how much money Kentuckians for Strong Leadership raised since forming in April 2013.