Barring a phenomenal last-weekend surge to Sen. John McCain (R-Ariz.), Sen. Barack Obama (D-Ill.) is our next president. The question is: Who is Barack Obama?

[IMGCAP(1)]After 22 months that he’s been campaigning, after thousands of speeches, dozens of debates and reams of position papers, it’s still not clear if he is a pragmatic post-partisan unifier or a populist liberal ideologue.

Some conservatives think he’s further out than that — a dangerous radical who really is a pal of unrepentant former Weatherman Bill Ayers and a disciple of the Rev. Jeremiah Wright — but the evidence for that from his campaign behavior is next to nonexistent.

But as Obama delivered his “closing argument” this week, beginning Monday in Canton, Ohio, it remained impossible to tell how far left Obama will tilt on economics or how energetically he will reach out to Republicans.

Obama’s appeal to independents (like me) has always been in lines like this one from Canton: “Understand, if we want to get through this [economic] crisis, we need to get beyond the old ideological debates and divides between left and right.

“We don’t need bigger government or smaller government. We need a better government — a more competent government, a government that upholds the values we hold in common as Americans.”

It’s pretty clear that, under Obama, the size of government will grow. It will regulate more. It will spend more on health care, energy, education and infrastructure. And it will tax more. The question is: How much? Is Europe his idea of the good economy?

We may get some partial answers immediately after the election, if Obama takes a leading role — as he should — in determining the size and shape of the Democratic Congress’ second stimulus package, now renamed the “recovery package.”

Will Obama tell Democratic leaders that he wants tax cuts to be part of the package, as well as government bailouts to states, expanded unemployment benefits and infrastructure programs? Tax cuts do stimulate investment and create jobs — and they also appeal to Republicans.

The chances are that Congressional Democrats will fare even better in the elections than Obama does. If they gain, say 30 House seats and eight in the Senate and he beats McCain by, say, 53 percent to 46 percent, Congressional leaders may think they have a mandate to govern bigger than his.

Speaker Nancy Pelosi (D-Calif.) has shown little inclination to be restrained in her liberalism either by Republicans or conservative Blue Dog Democrats.

And, if Senate Majority Leader Harry Reid (D-Nev.) can muster 60 votes to thwart GOP filibusters, it’s President Obama who’ll have to insist on inviting GOP input into governing decisions.

On energy, for instance, will Obama face the reality that America will be dependent for 20 years or more on fossil fuels and agree with Republicans on the need for offshore drilling — and also, ready-to-build nuclear plants — or yield to carbon-phobic environmentalists who dominate his party?

Trade unions have contributed generously to the coming Democratic victory, and they will expect to be repaid.

In Canton, Obama said “when it comes to jobs, the choice in this election is not between putting up a wall around America or allowing every job to disappear overseas.”

But the AFL-CIO has never seen a foreign trade agreement it could support. Will Obama really abandon allies like Colombia — whose experience it could use in combating the drug trade in Afghanistan — in order to satisfy the unions?

And, what about trial lawyers, the largest group contributing to Obama’s campaign? They will doubtless try to get Congress to expand their ability to file suits in state courts — against drug companies, for instance, even though their products have to pass muster at the Food and Drug Administration. Will Obama support that?

“When it comes to health care,” Obama said in Canton, “we don’t have to choose between a government-run health care system and the unaffordable one we have now.” But will he listen to GOP arguments that a major way to control rising costs is to empower consumers to make health care choices?

In Canton, Obama said, “I will put in place common-sense regulations … so that Wall Street can never cause a crisis like this again.” It’s clear, there needs to be regulation to make sure credit-rating agencies do their jobs honestly and opaque “derivatives” are made transparent.

But there is also a danger of over-regulation that stifles innovation — and will Obama agree, as Republicans have long argued, that Fannie Mae and Freddie Mac also need to be regulated, which Congressional Democrats oppose? He has never mentioned it.

On foreign policy, will Obama really depart Iraq “carefully”? If he doesn’t, that country’s collapse into new sectarian strife could be his first disaster.

It was impolitic for Sen. Joseph Biden (D-Del.) to say it, but Obama’s “mettle” will be tested very soon — not only by foreign foes, but his domestic allies. Let’s hope he’s the man we hope he is.