DETROIT -- The center of the Republican universe has finally been located, somewhere between the Lamborghini display and the General Motors pavilion at the Detroit auto show.

All three leading GOP candidates passed within shouting distance of each other here this afternoon, in an apparently deliberate bit of gamesmanship the night before polls open in the Michigan primary. Mitt Romney gave a press conference in front of a fuel cell-powered GM SUV, while Mike Huckabee peered through the windows of a nearby hybrid. John McCain strolled through the front door to meet Joe Lieberman for a walk-through near the Ferraris. Each one had his own orbiting horde of TV crews, reporters and aides shoving their way through the automotive writers checking out concept cars and 2009 models.

For a moment, the media throngs were in danger of commingling. "You don't pay us to drive you around to Mike Huckabee events, I'll tell you that much," one Romney staffer told the reporters, including me, who had booked seats on a bus following Romney around Michigan all day.

The overlap wasn't an accident. While Romney (whose father, George Romney, was an auto executive before becoming Michigan governor) had always planned to swing by the car show after addressing the Detroit Economic Club this afternoon, McCain added his visit later, ditching his own traveling press corps to zip over to the Motor City from western Michigan. Polls show they're neck and neck here, and Romney has been hammering McCain -- who has been saying some of Michigan's lost jobs aren't coming back -- for giving up on the auto business; McCain, for his part, says he's just being honest. The Romney digs may have prompted McCain to show up here to show he, too, supports the Big Three.

Meanwhile, Huckabee -- lagging behind in polls -- apparently ignored a heads-up from Romney advisors hoping to give the two men a little more clearance than they had. On his own tour of the auto show, he somehow wound his way over to exactly where Romney was talking to the media (though when Romney aides yelled, "The bus is leaving!" to reporters, it must have briefly interrupted whatever point Huckabee was trying to make about how much he loves cars -- especially American ones). No debate ensued, which was sort of a surprise given that the GOP can't seem to go more than a day or two without one.

At any rate, only Romney -- the native son of sorts, even if he was elected governor of Massachusetts -- is staying in Michigan through when the polls close. By then, Huckabee and McCain will have moved back to South Carolina, which votes Saturday.