As the Republican presidential field took final shape this week, former Massachusetts governor Mitt Romney moved quickly to try to consolidate his support across the party, rallying key donors and elected officials by asserting that he is the candidate best positioned to take on President Obama next year.

The new burst of support is validation of Romney’s steady-as-she-goes strategy that, along with his return to the top of opinion polls, helps feed the notion that he’s starting to look like a winner.

But attracting support from the GOP establishment has never been Romney’s biggest challenge. To become his party’s nominee, he must do something he has never been able to do before: win over a broad swath of primary voters, many of whom suspect he is not as conservative as they are.

With a slew of would-be challengers taking a pass and his main rival, Texas Gov. Rick Perry, slipping in the polls, Romney will face a critical three-month stretch before the first votes are cast in Iowa. In that time, he must convince his party that he isn’t merely a satisfactory choice that they will simply have to stomach, but instead that he is a candidate they should be excited about.

On the stump, Romney has started talking more about his family as a way to personalize himself. He plans to roll out more policy specifics to help burnish his conservative credentials. He also is striving to convince voters that his executive experience in the private sector and his 59-point jobs plan make him the Republican most able to turn around the nation’s economy.

“As much as possible, we’re going to talk not about how Mitt Romney will win, but why he should win,” said Stuart Stevens, Romney’s chief strategist. “We’re going to talk about jobs and houses and immigration and foreign policy and America’s role in the world and big stuff.”

At the same time, his campaign is trying to build an aura of inevitability by gathering as many elected officials, major financiers and prominent party activists as it can around his candidacy.

On Wednesday, the campaign announced the endorsement of freshman Rep. Tim Griffin, who will serve as Romney’s Arkansas chairman. Also Wednesday, Romney met with Florida Gov. Rick Scott in Tallahassee to ask for his support. And he held an evening reception to enlist uncommitted state legislators.

But in the current climate, any Republican — especially Romney — is in danger of being tagged as the candidate anointed by party leaders. Among grass-roots conservatives, there is a strong distaste for the establishment. Thus, Romney’s advisers will have to manage that support in a way that doesn’t leave primary voters feeling as though their choice is being dictated by party leaders.

Although Romney’s national poll numbers have essentially remained the same all year, there are signs that he is connecting with voters where he has spent most of his time and where it matters most. He has amassed markedly stronger leads in some of the early-voting states, such as New Hampshire.

“He was very disciplined in the debates, he’s aggressively working the early primary states and he’s riding a message. That’s a winning combination,” said GOP strategist Scott Reed, who managed Bob Dole’s 1996 presidential campaign.

As he stumped across Florida this week, Romney talked less about Perry than he had previously, aiming most of his rhetorical fire at Obama.

“This week, the president said to the American people that he’s a warrior for the middle class. If that’s the case, I think there’s been a severe case of friendly fire,” Romney said in Tallahassee during a Wednesday lunchtime visit to the Seminole Wind restaurant.

Through the many flirtations with various other candidates, Romney has been selling himself as the steady, sensible choice.

As if to make this point, he sidled up to the lunch buffet line at the Seminole Wind and took two pieces of fried chicken but then made a beeline toward the vegetables. “I know what I should be eating,” he quipped, filling his plate with black-eyed peas, collard greens, okra and tomatoes, lima beans — “I love lima beans” — steamed cabbage and Brussels sprouts. By the time he finished his meal, he remarked that he hadn’t touched his chicken. “I’ve got to eat my veggies,” he said.

Romney is talking more about big themes. During a town hall meeting Tuesday in the Villages, a massive retirement community in central Florida, he cast himself as a leader who could help the country overcome its challenges and “keep America as it has always been — the strong, the mighty, the good and the hope of the Earth.”

On Thursday, Romney will speak with veterans on the USS Yorktown, a World War II-era aircraft carrier in Mount Pleasant, S.C., and on Friday, he will deliver a major foreign policy address at the Citadel in nearby Charleston.

At the Villages, Romney was introduced with great fanfare as “the turnaround leader.” One man stood up and said: “Mr. Romney, you may have heard this before, but you look very presidential.” And after his 50-minute town hall meeting, Marilyn Lanzone, 70, came up to ask for his autograph. “Mr. Governor,” she said. “I hope the next time you come we’ll be saying, ‘Mr. President.’ ”

Romney seemed to revel in the moment, observing several times: “It’s always a beautiful day at the Villages.”

But he knows he hasn’t closed the deal. He is preparing to be pummeled with a new wave of attacks, and he knows he needs to show that he can take a punch. Perry’s campaign has been stepping up its efforts to cast Romney as a flip-flopper, a label that dogged him in 2008, by saying Romney lacks core convictions and has shifted positions.

After announcing on Wednesday that it had $15 million in cash on hand, the Perry campaign left no doubt that it can afford to put such attacks on the airwaves in early-primary states.

Romney’s supporters question whether such attacks will actually move voters, considering most Republican primary voters already know that he championed a state health-care overhaul in Massachusetts and that he previously had more moderate positions on social issues.

Republican strategists not aligned with any candidate agree that Romney has improved as a candidate not only since his 2008 run, but also over the past few months. On the stump, he has become sharper and more passionate. Romney’s confidants say he thrives on competition, and the rise of Perry presented the first real threat to Romney’s path to the nomination.

“He knows the nomination process is a marathon and has paced himself well. He’s in top condition and could win the nomination through sheer perseverance, dedication and determination,” said Mark McKinnon, a top strategist on George W. Bush and John McCain’s presidential campaigns. “But he should also be prepared for a few more surprises along the way that could trip up the best-laid plans.”

Cain’s dim view of Occupy Wall Street protesters

Fact Checker: Obama’s news conference Pinocchios

For Anita Hill, the Clarence Thomas hearings haven’t really ended

Perry disputes hunting camp story

Brown takes heat on comment about Warren