ABC News’ Jan Crawford Greenburg Reports: McCain’s tough new "celebrity" ad campaign, designed to portray Obama as an empty suit who — like Paris Hilton — is devoid of substance, is the first part of a broader strategy that ultimately could have ramifications for McCain’s VP selection. The campaign will continue to hit hard that Obama is not an agent of change — but a man who merely plays to his audience and is unwilling to risk losing his adoring crowds by making the tough decisions. This is only the first volley, sources close to McCain tell ABC News. There’s a bigger point — and this initial volley, they say, lays the groundwork for it. They will be sharpening McCain’s message that he, not Obama, is the true change agent, a man who’s repeatedly taken unpopular stands, made the hard calls and forged bipartisan alliances. Part of the calculus now is how his VP choice will further sharpen that message. There is significant support among top McCain advisers that he make a "transformative" pick who would change the Republican Party — someone who would appeal to moderate Republicans and Democrats. This pick would be someone who, like McCain, has taken the unpopular stands, made the hard calls and stood firm on principle. A person who fills that bill, these advisers say, is Joe Lieberman. Lieberman, an Independent Democrat, flatly denied his interest to ABC’s Ron Claiborne earlier this month, but McCain is now seriously considering him as that "transformative" pick, sources tell ABC News. McCain is close to Lieberman, admires his willingness to stand alone on principle and shares his views that Islamo-fascism is the most serious threat to the nation’s future. What’s more, some McCain advisers believe Lieberman would dramatically enhance the point they are now trying to make about Obama in this "celebrity" ad campaign. McCain and Lieberman are anti-celebrities, the argument goes. They have, as one top adviser said, felt the heat after taking unpopular positions because they were willing to do "what’s right for the country" — whatever it meant for their own popularity. Tom Ridge also would be that kind of pick — and he, too, is on McCain’s very short list, sources say. As a Republican who was Bush’s director of Homeland Security, he is less dramatic than Lieberman. He also ran into some problems at Homeland Security with his color-coding system. But as a moderate pro-choice politician and former Pennsylvania governor, he, too, could make a statement–and open the Party to moderates who now are up for grabs. And looking at the map, Ridge also could deliver Pennsylvania — a state McCain badly needs. McCain has not decided which route to take. The transformative pick would anger a slice of the base, and he could decide, at the end of the day, to pick the conventional conservative. That would be Mitt Romney, Minn. Gov. Tim Pawlenty or former Ohio Rep. Rob Portman, sources tell ABC News. But of those three, only Pawlenty would help with McCain’s "change" message. Romney, a flip-flopper extraordinaire, is vulnerable to the "celebrity" tag himself–and Portman is defined as Bush’s budget director.