Apparently in Barack Obama's world of post-partisanship, being Joe Lieberman means you never have to say you're sorry.

That's the conclusion one can draw from the Senate Democratic Caucus decision to give only a slap on the wrist to the Democrat-turned-independent who was Republican nominee John McCain's sycophantic shadow in the late presidential campaign, while uttering swipes at Obama.

The president-elect, according to Lieberman, urged the Senate Democrats to let bygones be bygones by taking it easy on him in the interest of unity, and they acquiesced.

The Democrats could have kicked Lieberman out of the party caucus altogether, or at least denied him his chairmanship of the Senate Homeland Security and Governmental Affairs Committee, for his apostasy. Instead, they voted by 42 to 13 to let him stay and keep that leadership post, along with the chairmanship of an Armed Services subcommittee, and took away his seat on the less glamorous Environment and Public Works Committee. Essentially, he got a free pass to continue thumbing his nose at the party he once served as its vice-presidential nominee.

Lieberman's Republican National Convention putdown of Obama as "an eloquent and gifted young man," even as he was lionizing McCain, mightily irritated a number of his Senate colleagues and former party buddies. But when it came to extracting retribution, they turned out to be a bunch of patsies.

Particularly grating was the way Lieberman throughout the campaign made himself the closest thing to McCain's Siamese twin, attaching himself to the GOP nominee at home and abroad. He could be seen occasionally whispering advice or corrections to his new best friend on occasions when McCain strayed factually from their mutually shared views, particularly regarding Lieberman's consistent fealty to Israel.

The Connecticut independent's pointed abandonment of Obama and the Democratic Party this year was not the first example of his penchant for biting a hand that has fed him. After the 2000 election, in which he shared the losing ticket with Al Gore — who had plucked Lieberman from relative obscurity by making him his running mate — he pointedly blamed Gore for the loss.

During a meeting of the Democratic Leadership Council, the moderate-to-conservative body of the party, Gore's ticket-mate charged that Gore's campaign pitch — "They're for the powerful, we're for the people," encouraged class warfare and was the undoing of Gore-Lieberman.

In 2006, Connecticut Democrats showed Lieberman the door in the senatorial primary, turning to liberal newcomer Ned Lamont. Declining to accept that rebuff, he ran as an independent in the general election and won with a big hand from new Republican friends.

When the Democrats seized control of the Senate later that year, he elected to vote with them to organize the body and was rewarded with a committee chairmanship and other plums. In gratitude, he continued his new independent ways, though he still voted most of the time with the Democrats.

As Lieberman seemingly flaunted his position as a critical vote in the slim 51-49 voting Democratic majority, resentment grew in the ranks, and conspicuously on the part of Senate Majority Leader Harry Reid, who had to look to him on close floor votes.

But as President Bush's plunging popularity began to suggest the possibility of a broader Democratic majority in the Senate after the 2008 elections, talk circulated within the Democratic brethren of giving Lieberman the heave-ho if it happened. Or at least denying him a committee chairmanship.

There was, however, always the implied threat that the one-time Democrat might cross over into the Republican ranks, an action that might jeopardize Reid's hopes to achieve a 60-vote, filibuster-proof margin in the Senate. At first it seemed the longest of long shots, but as the Obama candidacy gained steam, and more and more Democratic Senate candidates looked like possible winners, that hope appeared less of a dream.

Now that Connecticut Joe is back in the fold, if only as an undependable ally for the Democrats, he will be closely watched for any sign of genuine contrition for his party disloyalty. As far as he would go after the caucus that gave him almost total absolution for his errant ways was to say he regretted some of the things he had said about Obama.

Jules Witcover's latest book, on the Nixon-Agnew relationship, "Very Strange Bedfellows," has just been published by Public Affairs Press. Reach him at juleswitcover@earthlink.net.