New York ? Rick Santorum doesn’t care about the unemployment rate. Newt Gingrich has “more baggage than the airlines.” Both are Washington insiders who have bent their principles for money and influence.

So say Republican presidential candidate Mitt Romney and his allies.

That advertising playbook has helped make Romney his party’s likely presidential nominee and could offer a preview of what awaits President Barack Obama in this summer’s general election campaign.

Voters in early primary states have seen plenty of this ad strategy already: a torrent of attacks on Romney’s opponents along with a few positive spots about the GOP front-runner’s biography and business experience. The strategy, devised by Romney’s campaign and an allied independent group, has been focused and unforgiving, all but eviscerating the former Massachusetts governor’s rivals while portraying the candidate as an effective manager and devoted family man.

“The ads have been very effective,” says Jonathan Collegio, a spokesman for American Crossroads, a conservative-leaning super political action committee. They’ve catapulted Romney “into a very strong position in the Republican primary without going so far that he’s alienated swaths of independent voters.”

The general election phase of the campaign will tell whether that’s true.

One thing that’s certain is that the Romney team’s approach has successfully shepherded him through a primary season in which voters have been far more conservative than the candidate was perceived to be.

Romney’s team now faces a far greater challenge: persuading a more centrist general electorate to bounce Obama, who polling shows has much higher favorability ratings than Romney himself.

The Romney campaign and Restore Our Future, a super PAC supporting his candidacy, together have poured about $50 million into television ads in the primary campaign so far, according to information provided to The Associated Press by ad buyers. No other candidate or super PAC has come close to that level of spending.

Restore Our Future, which is run by several former Romney advisers, has spent more than $35 million on TV ads alone, almost of which have been negative attacks against Santorum and Gingrich.

ROF’s approach has been clear and unadorned: Cut straight to the heart of Romney’s rivals’ vulnerabilities, often using their own words against them. Make accusations about their records, citing news sources as support.