The man without a party, Sen. Joe Lieberman (ID-Conn.), came to the Republican National Convention and raised perhaps the key issue of the 2008 campaign when he declared “the McCain/Palin ticket is the real ticket for change this year.”

[IMGCAP(1)]“Change” is the key on two levels, the purely political and the real world. Who is seen as the “change agent” of 2008, and who can actually deliver the changes America needs to meet 21st-century competitive challenges?

Politically, Sen. Barack Obama (D-Ill.) has made change the touchstone of his entire campaign, and last week’s Democratic National Convention was devoted at least as much to painting presumptive presidential nominee Sen. John McCain (R-Ariz.) as “more of the same” and “George Bush’s third term” as to extolling the virtues of Obama and his agenda.

President Bush’s approval ratings currently average 30 percent, according to Real Clear Politics, and 75 percent of voters think that the country is on the wrong track. Voters clearly want something different.

Before the Denver convention, according to the Gallup Poll, 66 percent of voters were either “very” or “somewhat” concerned that McCain would continue Bush policies. Afterward, 64 percent were — although the number of “very concerned” went up from 41 percent to 47 percent.

On Tuesday night here in St. Paul, Minn., no speaker directly rebutted that impression, emphasizing instead McCain’s record as a “restless reformer” and “maverick” who could accomplish the change of fighting special interests in Washington and ending partisan gridlock.

Off the convention floor, at a breakfast with reporters, the McCain campaign’s policy director, Douglas Holtz-Eakin, cited global warming, “spending restraint,” and early attention to housing assistance and health care reform as examples of McCain differences from Bush.

But, as Democrats repeatedly emphasized, McCain — formerly opposed — has adopted Bush’s tax policy and the supply-side economics underlying it. While McCain presciently criticized Bush’s early Iraq strategy, their foreign policies are essentially the same.

And now, McCain has branded himself indelibly as a cultural conservative like Bush by naming Alaska Gov. Sarah Palin (R) as his running mate.

McCain personally preferred Lieberman and also considered former Pennsylvania Gov. Tom Ridge (R), but he balked after being warned that a pro-choice selection might produce open revolt at this convention.

So, he yielded to the right, picking a candidate that warmed the hearts of James Dobson, Rush Limbaugh, Pat Buchanan and the rest of the pro-life, pro-gun, anti-gay, anti-stem cell, abstinence-only, creationist right.

The McCain campaign emphasized Palin’s record as a tough reformer who took on Alaska’s corrupt Republican establishment and raised taxes on oil companies — an exemplary, if brief, record — but the fact remains that he yielded to the cultural far right when the chips were down.

What difference will it make politically? Palin’s selection has indisputably energized this convention and the conservative GOP base, and a Rasmussen poll published Wednesday showed that Palin made 43 percent of men more likely to vote for McCain versus 34 percent less likely. But 41 percent of women said they were less likely to support McCain versus 31 percent more likely.

At a focus group I attended Sunday sponsored by AARP and conducted by GOP pollster Frank Luntz, one undecided female participant — a Sen. Hillary Rodham Clinton (D-N.Y.) delegate in Denver — declared that McCain’s “age didn’t really bother me until he picked Palin.

“What if he dies in office and leaves her as president? She leans toward the rigid right and I always thought he was a moderate.

“You know, I change my mind almost every day, but right now I’m wondering where the John McCain I really liked in 2000 went. What happened to the moderate?”

She added that she still wasn’t convinced by Obama, who she described as too inexperienced. A Gallup Poll published Tuesday showed that the percentage of Clinton voters planning to vote for Obama jumped from 70 percent to 81 percent after the Denver convention, although 12 percent said they will vote for McCain.

In the end, vice presidential nominees don’t usually affect the outcome of an election much unless they prove to be disasters — which isn’t happening yet to Palin, despite attacks from the left.

What counts is how voters judge the presidential rivals.

What ought to count this year is whether they really will deliver change — both in policy and governance.

Although McCain has adopted Bush’s tax policies, there are elements of his economic agenda that would spur faster job growth — chiefly, corporate tax cuts — and help middle-class families, including job training reform and an increase in the child tax credit.

As Holtz-Eakin pointed out, McCain also favors means-testing Medicare benefits, reducing corporate subsidies, putting “everything on the table” to reform Social Security and reaching an energy-environment accord with Democrats to set the stage for bipartisan agreement on other issues.

While McCain, born in 1936, comes across as a quintessential 20th-century politician, his economic program could help the United States adapt to 21st-century competitive challenges — provided he’s also willing to invest in education and infrastructure instead of simply slashing domestic spending.

And while Obama, born in 1961, seems a 21st-century figure, his and (especially) his party’s economics are a throwback to the New Deal and Great Society — redistributionist, high-tax and heavy on government regulation and direction, beholden to labor unions and trial lawyers. But he does favor investment in human capital and infrastructure.

For McCain to help himself win this election, he needs to draw a vivid picture of how his agenda is different from Bush’s and how it will translate into a more competitive economy that can maintain America’s high standard of living.

That’s what Obama tried to do in his Denver acceptance speech — and got a modest bump in the polls as a result.

At the focus group I attended, fewer than half of the participants raised their hands when asked if America would be the No. 1 nation in the world 10 years from now and whether their children would live a better life than they do.

Altering that perception is the change voters want — and America needs.