Washington ? Last Wednesday morning, The Washington Post published a poll of registered voters giving Barack Obama an eight-point lead – largely because the voters said they trusted him more than John McCain on handling their No. 1 issue, the economy, by an astounding 19 percentage points.

That noon, I had lunch with two veteran Republican operatives not working in the McCain campaign and asked them what they would recommend for the Arizona senator.

“Get Alan Greenspan to run with you,” said the first. “Or Warren Buffett,” the second offered.

Neither of those celebrated financial wizards is likely to be available. But it got me thinking about the question of whether the vice presidential choice offers McCain a way to deal with his problem. I spent the rest of the afternoon on the phone, asking the same question of other Republicans.

Several suggested that McCain has been so candid about his own lack of expertise in economics that he cannot hope to build personal credibility on that issue. Instead, he could be well advised to tell the public that he wants his running mate to be the “deputy president” for domestic affairs, while McCain handles the issues of war, peace and national security.

But who?

Former House Speaker Newt Gingrich did not equivocate. “I’m for Bobby Jindal,” the freshman governor of Louisiana, he said. “He’s the smartest governor in the country. He’s got youth, energy, optimism.” And, Gingrich said, as the son of Indian immigrants, “Jindal represents the most successful entrepreneurial culture in the world.”

Several others expressed admiration for Jindal, but, as the afternoon wore on, there were three other names that came up more often – though each had notable drawbacks.

One was New York Mayor Michael Bloomberg. He showed his financial prowess by building a multibillion-dollar journalistic enterprise, specializing in Wall Street and employing all the high-tech tools of the new media. Then he jumped into politics, running as the Republican candidate for mayor after being a lifelong Democrat. Lavishly self-financed, he won twice in that Democratic city, and then declared himself an independent.

Bloomberg has been an innovative, successful mayor, but one person I interviewed said that, given his political history, “there would be an absolute donnybrook” at the GOP convention if McCain picked him. Besides, this Bloomberg friend said, the only job the mayor wants is secretary of state, “and he’s not qualified for that.”

The second name I heard was Rob Portman, the former trade representative and budget director in the Bush administration and, before that, an admired member of the House of Representatives. Portman is plenty smart, very smooth and respected on Capitol Hill and abroad.

He is from Cincinnati – in the always crucial swing state of Ohio – and his many friendships on both sides of the aisle in Congress could be an asset to McCain in dealing with what is likely to be a Democratic majority.

But the problem is, as one Republican told me, “he is totally tied to the Bush administration,” which he left just a year ago. “As budget director, he had to sign off on everything they did.”

The third and final name that was frequently mentioned was Mitt Romney, McCain’s closest challenger for the nomination. Like Bloomberg, he built a spectacularly successful private-sector career for himself before winning his first public office as governor of Massachusetts. He has strong family ties to Michigan, a potential battleground, and he won friends in many other places while campaigning for president.

On paper, Romney looks perfect – great looks, a wonderful family and squeaky clean. But there is a problem.

McCain, who rarely develops a strong personal distaste for another politician, Democrat or Republican, expressed disdain for Romney, publicly and privately, when they were opponents. He came to believe that Romney was a serial flip-flopper, devoid of strong convictions. He was not alone in that judgment, but for McCain, that was a serious failing.

Since their contest ended, Romney has proved his loyalty by joining McCain on several successful fundraising trips. Many Republicans outside the intimate McCain circle are lobbying hard for him to pick Romney.

But McCain relies on his instincts for the big decisions, and I can’t tell whether he has really abandoned his initial thumbs-down judgment about Romney. He clearly needs help from someone to compete with Obama on the economy. Greenspan and Buffett aren’t going to do it for him.