Emptiest threat of the week (so far): Organized labor's purported vow to hold President Obama accountable if he fails to fulfill his promises to organized labor.

In a speech today, Richard Trumka, the incoming AFL-CIO president, is expected to make that vow crystal clear; as one of his aides told the press earlier this week, "We're going to hold the politicians we've elected accountable more than we have in the past," and "there will be consequences" for any Democrat who makes nice to labor but fails to follow through.

Yeah, sure.

If Obama fails to go to the mat for organized labor's top issues - a health care public option, a law making it easier for workers to unionize, a broad crackdown on imports that threaten domestic union jobs - where exactly is the AFL-CIO and its 10 million members supposed to go? To the Republicans?

Organized labor has few political options, in large part because it has long been suffering an inexorable slide. After World War II, roughly 35 percent of all American workers were unionized; today only 12.4 percent are unionized. Worse yet, only 7.6 percent of private sector workers are currently unionized. The reasons have long been clear - domestic manufacturing jobs have eroded, market globalization has expanded, younger members of the work force have no affinity for unions if they even think about the issue at all - and, in political terms, this means that labor's threat to punish a wayward Obama should be viewed very skeptically.

I heard the same chest-thumpings 14 years ago. In the autumn of 1995, when the AFL-CIO met in New York to elect Trumka's predecessor, labor was all ticked off at Obama's Democratic predecessor. Unionists complained that Bill Clinton merely talked a good game, only to screw labor by going to the mat for the NAFTA trade deal that, in labor's view, would prompt more American firms to shift jobs over the border. They complained that Clinton had promised a new law that would bar firms from replacing strikers with permanent new hires - but, in his first two years, he couldn't even persuade his Democratic Congress to enact it.

They were also incensed that Clinton had told a group of affluent Texans that he was sorry he had raised their taxes in 1993; as union activist Vic Fingerhut told me, "Unbelievable! He's still chasing after people who have uttter contempt for him, who still think he's a socialist." Another activist, Donald Sweitzer, wondered, "Does he have it in him to be a fighter? I don't know." A number of them groused to me that organized labor might lash back at Clinton by refusing to work hard one year later in the 1996 elections. But, of course, that never happened; they swallowed their concerns about Clinton because the alternative - a rising GOP under House Speaker Newt Gingrich - struck them as far worse.

The same pattern occurred in 2000. That spring, organized labor was furious that Clinton had engineered a free-trade pact with China - and that veep Al Gore, the likely '00 nominee, had stood with Clinton is support of a deal that could imperil American jobs by flooding these shores with imported goods. So labor's leaders vowed to retaliate against Gore. Richard Trumka - the same guy now heading the AFL-CIO - warned in May that union members "are going to stay home" in November. There was talk of "taking revenge" on the Democratic ticket; labor strategist Victor Kamber told me, "Anyone who thinks that the anger will dissipate just doesn't understand labor."

Yeah, sure. The anger dissipated. Organized labor busted its butt for Gore that November, because it knew that George W. Bush would ill-serve its interests. And indeed he did.

Which means that, when the chips are down politically, Obama has all kinds of wiggle room with the union leaders. What are they going to do - defect to Mitt Romney (who once ran a private equity firm that bought companies and laid off a lot of people)? Or Mike Huckabee (who hails from the right-to-work state of Arkansas)? Or Sarah Palin (no description necessary)? Or neoconservative ideologue Rick Santorum (who represented a strong union state until he was slaughtered in 2006 by 18 percentage points, the worst defeat of a Senate incumbent since 1980)?

No way. Nothstanding all its current threats to hold Obama accountable, the labor bigwigs will be pleased just to have seats at Obama's table, and they'll stay there, even if the servings are lukewarm.

Speaking of Santorum, he has voiced the worst hypocrisy of the week (so far). In a conference call with reporters yesterday, sponsored by the Republican party, the ex-Pennsylvania senator said it would be an "abomination" for the Senate Democratic majority to pass health care reform via the parliamentary maneuver known as the "budget reconciliation process," which requires only 51 votes as opposed to the filibuster-proof 60 votes. (The White House and the Senate Democrats have made no decision to use that maneuver, but let us continue.) Santorum argued that health care reform was not an appropriate issue to pass in that manner; in his words yesterday, "this is a major policy initative in an area that goes beyond the federal government's balance sheet."

But then a reporter helpfully pointed out to Santorum that, during the Bush era, the majority Senate Republicans had used the 51-vote budget reconciliation maneuver to pass the bill that would mandate drilling for domestic oil in the Arctic National Wildlife Refuge. Uh: Wasn't the ANWR bill a major policy initiative on an issue that went beyond the balance sheet?

Behold Santorum, twisting like a pretzel: "Well, again, you're talking about a situation where, again, the biggest thing about drilling is certainly it has an impact on a small chunk of land in northern Alaska, and it has an impact on the federal revenue, but it's not a particularly complex thing." Besides, "the impact on the 350 million Americans for drilling a few holes in Alaska is fairly minor, as far as how it affects their daily lives."

Yeah, drilling in Alaska was "fairly minor," and therefore it was OK to pass it via the 51-vote maneuver. But that doesn't square with what Santorum said in 2006, when he declared that drilling in Alaska "has the potential to play a significant role in reducing our dependence on foreign oil." And his sudden objections to the 51-vote maneuver don't square with the fact that, in 1995, he helped lead the way on a Senate GOP effort to pass welfare reform via that very same maneuver.

Santorum has signaled again this week that he might seek the '12 GOP nomination. Maybe Democrats should start giving him money.

Best trial balloon rumor of the week (so far): This one is particularly delicious.

There are reports out of Boston today that the Massachusetts Democratic legislature is now leaning toward changing state law so that the Democratic governor can appoint an interim Democratic senator - who could then provide the filibuster-proof 60th vote for health care reform this autumn. Apparently some of the Democrats are furious about Joe Wilson's insolent outburst, and now want to pay back the GOP by ensuring that Senate Democrats have the votes to pass reform.

As I noted late last month, changing the law would be hypocritical - given the fact that it was once legal to appoint an interim senator, until Massachusetts Democrats banned the practice back in 2004. At the time, they were worried that if John Kerry ascended to the White House, then-governor Romney would replace him with an interim GOP appointee. But now, in a situational flip-flop, they're reportedly leaning toward reinstating the interim appointee option.

But that's not the delicious rumor I promised you.

No, the trial balloon being floated by a number of political people is that a strong candidate for an interim Senate appointment would be none other than...Michael Dukakis.

And why not? The 1988 presidential nominee is 75, fit, tanned, rested and ready. He could serve for four crucial months, until the January special election. He's a policy wonk who loves the health care issue. He could go to Washington and, with a few key votes, put the screws to the opposing party that once smeared him as a rapist-coddling, harbor-polluting, flag-disrespecting girly man.

"Revenge of the Duke." The story would write itself.