"He is the most ill-prepared person to assume the presidency in my lifetime," Christie told some 600 Kentucky Republicans at a Lexington hotel. "This is a guy who literally is walking around in a dark room trying to find the light switch of leadership."
Christie was in Kentucky to deliver a pep talk to state GOP leaders. The state's presidential primary is Tuesday, though it will have no significant impact. Former Massachusetts Gov. Mitt Romney is the presumptive Republican presidential nominee.
In his remarks, Christie focused entirely on the general election, drawing a standing ovation for his biting remarks about Obama.
"He has sat in the Oval Office and cared more about posing and preening and making partisan politics the rule of the day in Washington D.C. than he's cared about progress," the New Jersey Republican, now in his third year in office, said of Obama.
Senate Republican Leader Mitch McConnell, who invited Christie to Kentucky, called him "the perfect conservative messenger to inspire and energize Kentuckians" to help defeat Obama this fall.
Although Romney is the only GOP hopeful still standing, Newt Gingrich, Rick Santorum and Ron Paul will be on state ballots when Blue Grass State voters go to the polls.
Paul effectively ended his presidential campaign several days ago when he announced he'd no longer be spending money on the race. Gingrich and Santorum withdrew, but not in time to have their names taken off the ballot.
Christie was touted last year as a potential presidential candidate, but he opted not to enter the race. He still is being mentioned as a potential running mate for Romney, as are others including Sen. Rob Portman of Ohio, Sen. Marco Rubio of Florida, former Florida Gov. Jeb Bush, Rep. Paul Ryan of Wisconsin and Virginia Gov. Bob McDonnell.
Christie endorsed Romney last October. He didn't address the running mate issue during his speech in Lexington. He was ushered in and out of the Marriott hotel ballroom without speaking to reporters.
Although Christie has said repeatedly that he loves his current job and does not have designs on being second-in-command, he has also said he would listen if Romney reached out to him.
Christie urged Kentucky voters to work hard to defeat Obama.
"Now listen," he said, "this country's problems are too serious, too serious, to spend another day with a bystander in the oval office."
Get Eyewitness News Delivered