COLUMBUS, Ohio — President Obama on Saturday formally kicked off his reelection bid with a speech in which he sought to re-energize young voters and make the case that his administration has moved the country forward.

In a speech Saturday afternoon at Ohio State University in Columbus, his first of two campaign kick-off events, Obama also took aim at his rival, presumptive Republican nominee Mitt Romney. He seized on some of Romney’s wealth-related campaign-trail missteps as he argued that the former Massachusetts governor is out of step with the middle class.

“I don’t care how many ways you try to explain it — corporations aren’t people. People are people,” Obama told the crowd about halfway through his 35-minute remarks.

He also tied Romney to congressional Republicans. As he has in previous campaign-trail events, Obama argued that the congressional GOP agenda includes tax cuts for the wealthy and cuts to Medicare and education, and would “give banks and insurance companies even more power to do as they please.”

“And now, after a long and spirited primary, Republicans in Congress have found a nominee for president who has promised to rubberstamp this agenda if he gets the chance,” he said.

And as the Romney campaign has argued that 2012 will be a referendum on the president’s handling of the country’s still-struggling economy during his three years in office, Obama on Saturday defended his administration at length, contending that the economy was a “house of cards” even before he took office.

“It will take sustained, persistent effort — yours and mine — for America to fully recover,” he told the crowd.

U.S Sen. Sherrod Brown, former Ohio governor Ted Strickland, and former senator and astronaut John Glenn appeared with the president in Ohio. Former Virginia governor Timothy M. Kaine and VCU men’s basketball coach Shaka Smart will attend the president’s rally in Richmond.

By some measures, the Ohio event fell short of expectations: According to the local fire department, Obama spoke to a crowd of about 14,000, well short of the arena’s 18,300-person capacity. Campaign officials said before the event that they had been expecting an “overflow” crowd.

But by others, it lived up to them. Both Obama and first lady Michelle Obama, who spoke directly before the president, received a roaring reception from the crowd. At several points during the event, the crowd interrupted the Obamas and burst into cheers of “Four more years!”

In brief remarks before the president took the stage, Michelle Obama focused on her husband’s biography in a subtle contrast with that of Romney, whom the Obama campaign has frequently sought to portray as wealthy and out of touch.

“Believe me, Barack knows what it means when a family struggles. . . . He knows what it means when someone doesn’t have the chance to fulfill their potential,” she said.

On her dress was a teal-blue flower pin — the same pin that she wore as she delivered her 2008 speech to the Democratic National Convention in Denver.

Both the Ohio rally and an event later Saturday in Virginia were intended by the Obama campaign to showcase its technological firepower in engaging supporters and gathering information about them to serve the campaign through the fall.

Campaign workers carried iPads to collect attendees’ names and contact information. “Pop-up” field offices were intended to give supporters a feel for what happens at a real campaign office — and allow them to volunteer and work phone banks on the spot.

Large screens at the two “Ready to Go” rallies displayed comments and pictures from supporters following the events on Twitter, Facebook or Web sites were set up so rally-goers could “check in” on various social networks to let their friends and family know they were there. And attendees were encouraged to sign up for text messages, which required handing over their cellphone numbers.

The stagecraft reflects the Obama campaign’s huge investment in technology to reach new voters and gather information from them, particularly the young people that Saturday’s two campus rallies were expected to draw. The campaign is also seeking to reconnect with those who turned out for Obama in 2008.

Just how engaging these tactics will prove is unclear. Campaign advisers who spoke on the condition of anonymity seemed as focused on the mobile devices used to collect data as on selling what the president would say.

Even Vice President Biden, who sent a campaign e-mail to supporters Friday with the subject line “Get your note and name on the big screen,” jumped in to promote some of Saturday’s bells and whistles.

“This is pretty cool,” Biden wrote. “Messages from supporters across the country will be broadcast on the big screen live during the event.”

Meanwhile, Romney’s team, which sent surrogates to both events to provide critical commentary, seized on what advisers described as a set of rallies likely to be long on gimmicks but short on substance.

“No matter how many lofty campaign speeches President Obama gives, the fact remains that American families are struggling on his watch: to pay their bills, find a job and keep their homes,” Romney campaign spokeswoman Andrea Saul said in a statement. “While President Obama all but ignored his record over three and a half years in office, the American people won’t. This November, they will hold him accountable for his broken promises and ineffective leadership.”

In his Ohio speech, Obama also highlighted his foreign policy — an area that has come into particular focus this week with the anniversary of Osama bin Laden’s death.

“For first time in nine years, no American is fighting in Iraq,” Obama told the crowd. “Osama bin Laden is no longer a threat to this country. Al-Qaeda is on the path to defeat. And by 2014, the war in Afghanistan will be over.”

Obama argued that Romney, by contrast, “said it was tragic to end the war in Iraq.”

“He said he won’t set a timeline for ending the war in Afghanistan. I have. And I intend to keep it. After a decade of war that’s cost us thousands of lives and billions of dollars, the nation we need to build is our own,” he continued.

In a preview of things to come, Obama also focused on issues not related to the economy but that have come to dominate the political debate, such as the DREAM Act and the battle over contraception — a fight that Democrats believe works in their favor.

“We don’t need another political fight about ending a woman’s right to choose or ending Planned Parenthood or taking away access to affordable birth control,” Obama said. “I want women to control their own choices.”

As he argued that “this election will be even closer than the last,” campaign operatives on Twitter were waging a battle of their own over perceptions of the rally and the lower-than-anticipated turnout.

“View from floor during @BarackObama speech. Not the ‘overflow’ crowd he promised,” tweeted Romney spokesman Ryan Williams, who attended the event as part of the Romney camp’s “bracketing” strategy.

Democratic National Committee spokesman Brad Woodhouse tweeted back a photo of a much-panned Romney event in Michigan, where the former Massachusetts governor held a small-turnout event in a massive stadium.

“Oh please,” Woodhouse tweeted.