Chief correspondent

Republican Mitt Romney will formally launch his second campaign for the White House on Thursday with an operation leaner and wiser than it was four years ago and a message singularly focused on what he sees as President Obama’s greatest area of vulnerability: jobs and the economy.

Romney and his advisers are working backward from November 2012. They believe that the economy will decide the outcome of the election and that the president has yet to convince voters that his economic policies have worked. They argue that Romney’s long experience in the private sector — his tenure as an elected official was just four years — makes him the Republican best positioned to challenge the president on how to fix what’s wrong.

“This election is going to be a referendum on President Obama and his handling of the economy,” said campaign spokesman Eric Fehrnstrom. “He didn’t cause the economic recession, but his policies have prolonged it and deepened it in some respects. We wondered what it would be like to elect a president who has no experience. Now we know.”

Democrats dispute all that and say Romney’s vulnerabilities on economic issues are far greater than the president’s. “The president made the hard choices, exercised sound judgment, and his policies are helping American industry give people jobs again,” said Democratic National Committee press secretary Hari Sevugan. “Mitt Romney made no choices, exercised bad judgment and has a record of helping big business take jobs away.”

Still, the president’s team has already shown it takes Romney’s candidacy seriously. The first video ad aired by a newly formed independent group that is run by two former White House officials targeted Romney.

When Chrysler paid back its government loan last week, a success for the president, the DNC blasted Romney for having opposed the auto bailout. Romney’s camp responded that he had favored a managed bankruptcy — a course they claim Obama eventually pursued. The argument is surely the first of many to come between the two camps.

The former Massachusetts governor begins as the front-runner for his party’s nomination, but hardly a prohibitive favorite. He narrowly leads the field in the latest Gallup poll, but the Gallup organization also called him “the weakest front-runner in any recent Republican nomination campaign.” He will be severely tested by his GOP rivals, who will all begin to target him.

Romney’s goal, according to advisers, is to keep his eyes on the bigger prize and to run his own race, not one dictated by the other GOP candidates or by the round-the-clock media culture. His hope is to convince Republican voters that, whatever flaws they may see in him, he is still the strongest candidate for the general election.

A series of interviews with Romney’s top advisers reinforced that message. “The economy is not just a talking point,” said campaign manager Matt Rhoades. “It’s the real deal. He [Obama] took his eye off the ball, doing all these other things. People are hurting out there. He’s the boss.”

Romney advisers see a disconnect between the president’s announcements of real progress on the economy at a time when there is, in the words of one, “a massive disaster out there with people’s lives.” They argue that, on economic issues, Obama still has trouble connecting with voters, particularly those from the white working class.

“He spent his entire political career running against Bush 43 [former president George W. Bush], crafting the argument, doing it better than anybody else,” said lead strategist Stuart Stevens. “And ever since that argument lost impact, he’s sort of been at sea.”

Connecting with working-class voters is a test Romney will have to prove he can pass. In polls of Republicans, he runs best among the college-educated and far less well among those without college degrees. Though he has shed his tie at many campaign appearances, he still retains more the look of the boardroom than the assembly line.

Romney believes his private-sector experience — only businessman Herman Cain in the GOP field can claim as much — will give him credibility on economic issues. “He can talk about it like [Arizona Sen. John] McCain [R] could about the military,” Stevens said. “You may not agree with him, but you don’t think he doesn’t know what he’s talking about.”

Much about this Romney campaign is different from the first. The candidate started slowly and kept his head down through most of the spring. He has focused on raising money — a national call-day two weeks ago produced pledges for more than $10 million — as a way to remind opponents that he is prepared to go the distance, if necessary, to win.

His few public events have been devoted almost exclusively to the economy. Those events have drawn little national attention, which, for now, suits Romney’s team.

Four years ago, Romney’s advisers would read the morning headlines or watch news breaks on cable TV and ask themselves how they could get their candidate into those stories. They needed to boost Romney’s profile.

Today, their candidate is a known quantity. They mostly refuse, as one adviser put it, to “chase the tennis ball.” They prefer to jump in only when it suits the campaign’s overall message, as they did this month after Obama gave his Middle East speech. Romney said Obama had “thrown Israel under the bus.”

The Romney campaign has set up in the same office building, near Boston’s North End, that it used in 2008, but occupies far less space. The staff is smaller and more cohesive, the payroll is smaller, the number of consultants fewer and the strategy different. “If you’re going to run a message-driven campaign, which you’re allowed to do because of name ID this time, you can be a little leaner campaign,” Rhoades said.

Four years ago, Romney was more about process than message — gaming the early-voting states, running early ads to raise his profile and trying to convert that into credibility and support. Strategy became the message. This time, Romney hopes message becomes the strategy.

Four years ago, he made a bid for social conservatives that took him off his core strength — economic issues. His advisers say that won’t happen this time. They believe he has no need to re-litigate social issues and say he has found his comfort zone with the economy and with a campaign of a different style and pace. He is, said several advisers, “less frantic.”

The Romney team spends less time than in the past trying to anticipate what rivals will do or who they will be. “This go-round, it’s important not to think in those terms, not in terms of who’s getting in or out, which slice of the Republican Party we’re going to try to carve up,” said media adviser Russ Schriefer. “It’s much more about Mitt going out and talking about jobs and the economy and his experience and making his case.”

Calculations about this state or that state are being made when they have to be made. The decision to announce in New Hampshire on Thursday is a reminder of the critical importance that the Granite State plays in the team’s calculations. Beyond that, Romney’s advisers remain coy about just how they plan to navigate through Iowa or South Carolina, two states less hospitable than New Hampshire.

Many of Romney’s GOP rivals see the Massachusetts health-care plan, which included an individual mandate like the one in Obama’s plan, as a major vulnerability. Romney advisers know his rivals will try to beat him with it at every opportunity. Going forward, they will try to make the argument that all GOP candidates, including Romney, favor repealing Obama’s plan and that he has put out a proposal to replace it. No one knows if that gamble will work.

As for his refusal to apologize for the Massachusetts plan, they argue that Romney has shown conviction in the face of pressure to back off. That goes to the other issue that threatens Romney’s campaign — character. Four years ago, his rivals battered him as a flip-flopper. This year, they will question whether he does have the kind of core convictions his advisers claim. They will ask: Who is the real Romney?

How Romney handles that question may be his ultimate test. Here in Boston, the answer, repeatedly offered by his top advisers, is that the real Romney is the one who will stake his candidacy on the economy. They say that is the key to winning the nomination and the White House, and on that they sound defiant.

“To beat Romney,” Stevens said, “you’ve got to beat him on the economy.”