Mitt Romney’s lunchtime speech was delivered from the 30-yard line before 1,200 suited-up business leaders in folding chairs, in a stadium that usually holds 65,000. (Carlos Osorio/AP)

Friday was supposed to be the moment for Mitt Romney’s triumphant return to his birthplace, when he would use the cavernous Ford Field to deliver a policy address that established him as the lone Republican capable of both fixing the economy and beating President Obama.

But the event served up fresh evidence for Romney critics who say he can’t rise to the occasion and rally important elements of the GOP around his candidacy.

The lunchtime speech was delivered from the 30-yard line before 1,200 suited-up business leaders in folding chairs, in a stadium that usually holds 65,000. And his address to members of the Detroit Economic Club contained ideas the former Massachusetts governor has spelled out before.

One new tidbit came when Romney strayed from his prepared remarks to note that he has four cars, including his wife’s “couple of Cadillacs” — casually reminding voters in this economically depressed state of his wealth.

Romney was trying to show that he was gaining the upper hand in a contentious battle with Rick Santorum going into Tuesday’s Michigan primary. Santorum laid out his agenda for his first 100 days in office during an evening campaign stop in Michigan before jetting to Tennessee, a sign that he is also looking ahead to the following week’s Super Tuesday contests.

But at a moment when Romney wanted to project bigness and command, the optics of Ford Field did not help.

Michigan Attorney General Bill Schuette, Romney’s state campaign chairman, told reporters that Romney “lit up the house at Ford Field.”

Even Romney would probably not agree with that conclusion. He began his speech by warning his audience that it would be heavy on policy. “This is not exciting and barnburning, but it’s important,” he said. The crowd’s polite applause was lost in the silence that filled the massive indoor stadium.

Campaign officials said they were not responsible for the selection of Ford Field, and one adviser said he was “frustrated” that the speech was given in such a huge venue.

“I guess we had a hard time finding a large-enough place to meet — and this certainly is,” Romney said.

Some Republicans thought it was a bit too large.

“The pictures of an empty Ford Field are not helping Romney,” tweeted conservative radio host Laura Ingraham. “Poor staging and tepid response from hometown crowd.”

And this was Rush Limbaugh’s response on the air Friday: “Oh, look. Romney said his wife drives a couple of Cadillacs. . . . That’s how you relate to the people in Detroit.”

Democrats tweaked Romney for his showing all day. Obama campaign spokesman Ben LaBolt tweeted, “Romney speaks to empty stadium at monument to industry he would have let go,” while Democratic National Committee spokesman Brad Woodhouse e-mailed reporters a photo under the subject line, “They Just Can’t Get Enough of Mitt.”

The Detroit Economic Club arranged the event and sold tickets for it ($45 for members; $75 for non-members), and when two indoor venues sold out quickly, club officials moved the speech to Ford Field.

Beth Chappell, president and chief executive of the Detroit Economic Club, said in a statement: “The original plan was to host the Romney meeting in the atrium, which is where we host DEC meetings when at Ford Field. During our walk through with the security team there were further issues raised due to the size of the crowd so we moved the event to the field.”

As Romney wrapped up his remarks at Ford Field, he said, “This feels good, being back in Michigan,” and then reprised a riff that earned him mockery last week.

“You know, the trees are the right height,” he said. “The streets are just right. I like the fact that most of the cars I see are Detroit-made automobiles. I drive a Mustang and a Chevy pickup truck. Ann drives a couple of Cadillacs, actually.”

The Cadillac SRX, the luxury crossover vehicle Ann Romney drives — she keeps one at their San Diego beach house and a second at their Massachusetts residence — is Detroit-designed but assembled in Mexico. Its starting price is about $35,000.

According to the latest polls, Santorum’s lead has disappeared heading into Tuesday’s Michigan primary, and the Romney campaign has become increasingly confident about its prospects.

In his 23-minute speech, Romney detailed many of the policies he had already proposed to overhaul the tax code, curb spending, and address problems with Medicare and Social Security. He added a few new details about some federal programs he would shift to the states, such as food stamps and housing, and rehashed his plan to lower individual income taxes for everyone by 20 percent.

“We have not seen a failure to communicate,” Romney said of Obama. “We’ve seen a failure to lead, and that’s why I’m running for president. I want to restore America’s promise.” Romney frequently veered off the prepared text on his teleprompters — themselves a no-no among many Republicans who regularly chide Obama for using them. Once Romney said, “I love cars,” and later he noted that he would be a president “who, by the way, likes cars.”

Outside, a couple hundred members of the United Auto Workers rallied in the sleet to protest Romney’s criticism of the auto bailout. On the roof of a nearby parking garage, the workers placed signs bearing letters on the windshields of American cars that spelled out: “Romney: Let Detroit Go Bankrupt” — a reference to a 2008 opinion piece Romney wrote opposing the federal bailout.

Romney said Friday that he wants Detroit to become the “Motor City of the world” and added that the fate of General Motors should be “determined by the demands of the marketplace, not the preferences of bureaucrats in Washington.”

About an hour after the speech, Romney stopped by the Mitt, a new restaurant named for Michigan’s nickname — the state looks like a mitten on a map. Romney expressed delight at discovering something, anything, that shares his name.

“I’ve almost never met anyone with my name,” he said. “Maybe two people in the entire country have told me their name is Mitt — and that’s over a lifetime of listening for someone to say they’ve named their kid Mitt. Somehow that name just did not catch.”

But on a day filled with less-than-ideal imagery, here, too, was another example: T-shirts for sale that said “Mitt Happens.” Romney, who walked by the hanging shirts as he left the restaurant, chose not to buy one.