Not so long ago, Barack Obama was the darling of the anti-war Left. On a host of national security issues – Iraq, Iran, government surveillance of terrorists – Obama preached a friendly gospel and was worshipped in turn as a political “messiah.” The liberal grassroots, sensing a kindred spirit in the Illinois Senator, rewarded him with the Democratic nomination. Nothing could come between Obama and his base.

Now something has. In a word: reality. As he courts the national electorate, Obama can ill-afford to sing from the same activist hymnal that propelled him, ever so narrowly, past Hillary Clinton. So it is that to the hair-pulling dismay of his supporters, Obama is leaving the Left – for the moment, at least.

It started with Iraq. During the primaries, Obama ran as the candidate of immediate withdrawal. Cheering the anti-war faithful, he pledged to remove all troops within 16 months – facts on the ground be damned. That promise, indeed, endures on his campaign website, which states that “Obama will immediately begin to remove our troops from Iraq. He will remove one to two combat brigades each month and have all of our combat brigades out of Iraq within 16 months.”

Or will he? On the campaign trail, Obama is beating a hasty retreat from retreat. No longer wedded to precipitous withdrawal, he now avers that he will “refine” his position after meeting with military commanders in Iraq later this month. Obama maintains that his position remains unchanged, but the claim is untenable. Where previously he would have imposed artificial timelines, risking chaos and worse with a too-hasty exit, he now appears to accept that the responsible position is to defer to military strategists.

This alone has given his devotees fits. But Obama has gone further. Belatedly but still unpalatably for his former fans, he has upbraided the fons et origo of the netroots, MoveOn.org, for its smearing last fall of Gen. David Petraeus as “General Betray Us.” By mainstream standards, the criticism was of little consequence. But among a political cohort famously intolerant of dissent – witness their passionate hatred of Sen. Joseph Lieberman – it constituted a betrayal in its own right.

On Iran, too, Obama is a changed man. Last fall, he made much of Hillary Clinton’s support for a nonbinding resolution to designate the Iranian Revolutionary Guard as a terrorist organization. Though he missed the vote, Obama did not hide his disdain for Clinton’s position. As he lectured at the time: “I strongly differ with Sen. Hillary Clinton, who was the only Democratic presidential candidate to support this reckless amendment.”

But what was “reckless” then is all too reasonable now. Just last month, Obama revealed that he favored designating the Revolutionary Guard as a terrorist group after all. Likewise, Obama has stopped emphasizing his pledge, much admired on the left side of the blogosphere, to meet with Iranian leaders without preconditions.

If Obama’s deviations were solely rhetorical, the Left would have little cause to worry. As it happens, however, the senator’s votes have undergone a similar shift. Most prominently, Obama has reversed course on electronic wiretapping. Back when he was competing for the netroots’ support, Obama promised to filibuster any bill that offered retroactive immunity for telecom companies cooperating with the U.S. government. But last week he voted in favor of just such a bill.

Expectedly, the senator’s spurned supporters up in arms. Not only have establishment media like the New York Times bemoaned the “new and not improved” Obama, but his younger admirers have turned against him. On left-wing hubs like the Daily Kos, Obama has been savaged for his turnaround on the wiretapping bill. Ariana Huffington, writing on her vanity website the Huffington Post, bitterly condemned his “realstupidpolitik.” So badly has the faith in Obama been shaken that commenter on Talking Points Memo wondered dejectedly if “perhaps we should get off our high horses and stop believing in Obama as a messiah.”

Reassuring as this political divorce is, there is less to Obama’s repositioning than meets the eye. On Iraq, Obama’s position is nakedly opportunistic, capitalizing as it does on the universally acknowledged success of the surge strategy that he opposed. There is every reason to think that, should conditions in Iraq deteriorate, Obama would reverse himself again.

Obama can at least claim consistency for his position on Iran. That is not entirely to his credit, however. His newly hawkish rhetoric notwithstanding, Obama is still offering the same policy – “direct, aggressive, and sustained diplomacy” – that has manifestly failed to deter Tehran in recent years.

With respect to wiretapping, Obama voted wisely last week. But it is not insignificant that he also supported three amendments that would have vitiated the bill, among them a provision to strip communications companies of immunity – a measure that would make it much more difficult for private companies to cooperate with the government on counterterrorism efforts. It inspires no confidence in his judgment that Obama fails to understand this elemental point.

Still, this is a marked improvement from the Obama of the primaries. The country’s most liberal senator last year is more reluctant to play the part. To talk chalk this up to political expediency is to miss the point. Whatever his beliefs, Obama has shown himself to be a far shrewder politician than many imagined. Just as notable, his strategic feints have underscored that the antiwar Left’s positions on crucial national security matters are out of synch with the mainstream. If, as the netroots insist, the country has turned resolutely leftward on these issues, why then is Obama so eager to break ranks with them?  

Ultimately, Obama’s political evolution is not, to crib a phrase, the kind of change one can believe in. But it is a welcome change all the same.