In a web video, the former Massachusetts governor announced the establishment of a presidential exploratory committee, which marks the first significant step for any potential candidate. The video features Romney speaking directly into the camera at the University of New Hampshire and focuses largely on the state of the economy.
"This morning I spoke with a number of students here at the University of New Hampshire," Romney says in the video. "Like young people all over the country, they wonder whether they'll find good jobs when they graduate. Last week, in Nevada, I walked through a neighborhood with homes vacant or in foreclosure. Unemployment there is over 13 percent. Across the nation, over 20 million Americans still can't find a job, or have given up looking."
Romney says in the video that President Obama is to blame since the president and most of his advisers haven't worked in the private sector. "They just don't know how jobs are created," he says.
Romney raised $10.25 million in a single day after bringing together his network of wealthy donors to dial for dollars in a city with no shortage of them.
Romney's phone bank fundraiser at the Las Vegas Convention Center, much like one during his first attempt at the Republican nomination in 2008, was the centerpiece of a series of fundraising events that included a conference call with volunteers who were asked to solicit their friends and neighbors for donations.
"This is a big kickoff for us, for our fundraising effort. It's kind of a celebration," Romney told the more than 400 supporters tuned in to watch him host a brief town hall-style broadcast on Facebook. "It's important to me that we get that started, the ball rolling today."
Mitt Romney launched his presidential campaign in New Hampshire with a scathing attack on President Obama's economic record, pointing to several lagging economic indicators he called "President Obama's own misery index."
"Barack Obama has failed America," Romney said from a farm in Stratham. "When he took office, the economy was in recession. He made it worse. And he made it last longer."
More than 16 million Americans are out of work or have stopped looking for work, he said, unemployment remains above 8 percent, foreclosures are still at record levels and home prices continue to fall. On top of that, the national debt has grown, as have food and gas prices.
"These failing hopes make up President Obama's own misery index. It's never been higher," Romney said. "Mr. President, you've had your chance."
DES MOINES, Iowa - Not long after Republican presidential candidate Mitt Romney began taking questions following his stump speech at the Iowa State Fair, he got into something of a shouting match with a liberal heckler who Romney at one point implored simply to "let me talk."
In a line that was quickly seized by Democrats, Romney at one point said "corporations are people" as part of a response to a question from an audience member, who asked if he believed Social Security should be a part of deficit negotiations.
"Corporations are people, my friend," he said. "...Of course they are."
"Everything corporations earn ultimately goes to people," Romney continued, prompting guffaws from the liberal hecklers. "Where do you think it goes? Whose pockets? People's pockets. Human beings, my friend."
Mitt Romney stuck out his hand and challenged Rick Perry to a $10,000 bet at a Republican presidential debate, prompting Perry to decline because he is "not in the betting business."
At issue was Perry's claim that he read in Romney's book "No Apology" that the individual health care mandate Romney signed into law as Massachusetts governor "should be the model for the country."
"I know it came out of the reprint of the book, but, you know, I'm just saying, you were for individual mandates, my friend."
That seemed to anger Romney, who responded, "you know what, you've raised that before, Rick. And you're wrong."
"Rick, I'll tell you what -- $10,000 bucks, $10,000 bet," Romney continued, thrusting his hand in the direction of the surprised Texas governor.
After the initial Iowa caucuses vote count showed Romney with an 8 vote victory over Rick Santorum, less than three weeks later, with no clear explanation, the Iowa Republican Party declared Santorum the winner by 34 votes.
Speaking to voters at a town hall meeting in Manchester, N.H., McCain, the Arizona senator and former 2008 GOP standard bearer lambasted President Obama's record, warning him: "You can run but you can't hide - from your record of making this country bankrupt; from destroying our nation security, and from making this nation one that we have to restore."
Invoking his 2008 comeback win in the Granite State - where he bested Romney despite the former Massachusetts' governor's considerable New Hampshire ties - McCain expressed "some nostalgia" at returning to the state. But, he said, he returned "to make sure that we make Mitt Romney the next president of the United States of America - and New Hampshire is the state that will catapult him on to victory."
"The time has arrived for Republicans to choose a presidential nominee; a new standard bearer who has the ability and determination to defeat President Obama and the strongest commitment to returning America to prosperity and defending our interests and values overseas. I'm pleased to have made my choice, and to endorse Governor Mitt Romney for the Republican nomination for president," he added, in a statement sent out by the Romney campaign during the event.
The endorsement has the aura of a favor returned. Four years ago, Romney endorsed, and later campaigned for, the Arizona senator after announcing his own withdrawal from the race. The two had been fierce competitors in the days leading up to Romney's withdrawal last time around.
With just one day to go before the first-in-the-nation New Hampshire primary, Mitt Romney described his faith in the free market with words that came back to haunt him.
"I like being able to fire people who provide services to me," Romney said at a breakfast in New Hampshire, when talking about health care. "You know, if someone doesn't give me a good service that I need, I want to say, 'I'm going to go get someone else to provide that service to me.'"
The candidate was already facing criticism from his Republican rivals about his record as CEO of Bain Capital LLC, a Boston venture capital group that invested in struggling companies in an effort to turn them around.
In the remarks, about his belief in providing people with options, Romney -- who in Massachusetts enacted an individual health care mandate while governor -- spoke about the need to incentivize insurance companies.
"I want individuals to have their own insurance. That means the insurance company will have an incentive to keep you healthy. It also means if you don't like what they do, you can fire them," he said.
Mitt Romney defeated Newt Gingrich decisively in the Florida Republican primary in a victory that reestablished the former Massachusetts governor as the clear frontrunner for the Republican presidential nomination.
"I stand ready to lead this party and to lead our nation," Romney told cheering supporters in Tampa after his victory became clear.
Gingrich, meanwhile, vowed to fight on in the wake of a potentially-devastating loss, telling supporters, "we are going to contest every place and we are going to win, and we will be in Tampa as the nominee in August."
Gingrich wound up dropping out on May 2.
Republican presidential frontrunnner Mitt Romney, fresh off his victory in the Florida primary, drew fire from conservatives after remarking that he's "not concerned about the very poor" -- a remark that Democrats seized on.
Romney appeared on CNN and reiterated a point he's often made on the campaign trail -- that he's more concerned with the middle class than the very rich or very poor.
"I'm not concerned about the very poor. We have a safety net there. If it needs a repair , I'll fix it," he said. "I'm not concerned about the very rich.... I'm concerned about the very heart of America, the 90 to 95 percent of Americans who right now are struggling."
CNN anchor Soledad O'Brien asked him to clarify his remarks saying, "There are lots of very poor Americans who are struggling who would say, 'That sounds odd.'"
Romney responded, "We will hear from the Democrat party, the plight of the poor and there's no question it's not good being poor... but my campaign is focused on middle income Americans... people who can't find work, folks that have kids that are getting ready for college."
He went on to say that the nation has a strong safety net for the poor, including food stamps, Medicaid and housing vouchers.
Reality television show host Donald Trump injected himself into the race for the Republican nomination for president when he endorsed Mitt Romney.
"It is my honor, real honor, and privilege to endorse Mitt Romney," Trump said with Romney and Romney's wife Ann at his side for the brief announcement at a Las Vegas hotel bearing Trump's name.
"Mitt is tough. He is smart. He is sharp. He is not going to allow bad things to continue to happen to this country that we all love. So Gov. Romney, go out and get em. You can do it," Trump added.
Mitt Romney was the big winner on Super Tuesday, winning six of ten states, defeating his rivals in Massachusetts, Vermont, Virginia, Idaho, Alaska, and in the crucial race of Ohio.
Romney campaign communications director Eric Fehrnstrom was asked on CNN if he was concerned that the primary challenge from Rick Santorum and Newt Gingrich "might force the governor to tack so far to the right" that Romney will alienate moderates who would otherwise vote for him if and when he reaches the general election.
"Well, I think you hit a reset button for the fall campaign," Fehrnstrom responded. "Everything changes. It's almost like an Etch A Sketch. You can kind of shake it up and restart all over again."
Santorum's campaign pounced on the comment in a news release, with Santorum communications director Hogan Gidley saying, "We all knew Mitt Romney didn't have any core convictions, but we appreciate his staff going on national television to affirm that point for anyone who had any doubts."
"We made a decision over the weekend that while this presidential race for us is over for me, and we will suspend our campaign effective today, we are not done fighting," Santorum said at a press conference in Gettysburg, Pennsylvania.
Santorum did not endorse Romney in making his announcement, though he did vow to fight to defeat President Obama and help Republicans win the Senate in the fall.
In a statement, Romney called Santorum "an able and worthy competitor" and congratulated his often-bitter rival for his campaign.
"He has proven himself to be an important voice in our party and in the nation," said Romney. "We both recognize that what is most important is putting the failures of the last three years behind us and setting America back on the path to prosperity."
Santorum ultimately endorsed Romney on May 7.
Romney sailed to victory in the Texas GOP primary, earning 69 percent of
the vote and surpassing the 1,144 delegates needed to secure the
nomination. Texas Rep. Ron Paul, who announced earlier in May that he would no longer be actively campaigning in the race, earned 11 percent.
Romney's six-day, three-country trip, which was meant to exhibit his skills as a statesman, was riddled with gaffes and controversies. From comments questioning the U.K.'s preparedness to host the Olympics; to controversial remarks about the relationship between "culture" and economic success; to a scuffle between his traveling press secretary and reporters, Romney was ridiculed by the British media and skewered by Democrats.
"He certainly didn't prove to anyone that he passed the commander in chief test," said top Obama campaign adviser Robert Gibbs in a press call, seizing on the controversies as evidence of the former Massachusetts governor's leadership deficit.
Despite his troubles, however, the lasting impact of his missteps are questionable: The notion that voters will still care about Romney's trip abroad come November is debatable, and the candidate, back on U.S. soil, is swiftly refocusing his message to reflect the talking points he's been hammering home for months.
Senate Majority Leader Harry Reid, D-Nev., on blasted Mitt Romney for refusing to release his tax returns, and said the presumptive GOP nominee "makes more money in a single day than the average American middle class family makes in two years."
"The word's out that he hasn't paid any taxes for 10 years," Reid said on the Senate floor.
Romney dismissed the majority leader's comments as "baloney" on conservative host Sean Hannity's radio show, advising Reid to "put up or shut up" about the identity of his anonymous source.
Romney will be officially nominated at the Republican National Convention in Tampa, Fla., during a roll call vote on Tuesday, August 27 and he will accept the nomination with a speech Thursday night.
Steve Chaggaris is CBS News' senior political editor.
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