Monday’s report in Roll Call about Linda McMahon’s interest in another crack at a U.S. Senate seat has broader implications than whether she will be on the Republican ticket in Connecticut in 2012. While the professional-wrestling mogul hasn’t made any public statements about a future candidacy, it is assumed that her scheduling of an appointment with National Republican Senatorial Committee chairman John Cornyn of Texas means she is laying the groundwork for 2012.

Cornyn will probably encourage McMahon to run again, since Senate candidates who are prepared to loan their campaigns nearly $50 million, as McMahon did this year in her loss to Dick Blumenthal, don’t grow on trees. While her final vote total of 43 percent in what was otherwise a year of Republican victories wasn’t terribly impressive, the GOP has to hope that in another two years, more Connecticut voters will see her as a serious politician rather than as the former ring mistress of a televised freak show.

Deep-blue Connecticut remains, as they say, “the land of steady habits,” which means that whether or not McMahon runs, her Democratic opponent will be favored. But the big loser here is not any one of the obscure Connecticut Republicans who might otherwise be inclined to run in 2012. Rather, it is the man who currently sits in the seat that McMahon covets: Joe Lieberman.

Lieberman hasn’t said whether he will run for a fifth term in 2012, but a McMahon run means his prospects for re-election have now shifted from unfavorable to highly unlikely. In 2006, Lieberman overcame his defeat in the Democratic primary at the hands of anti-war candidate Ned Lamont by cruising to victory in November. But the formula for that victory as an independent was one that cannot be repeated. In 2006, the majority of Democratic voters rejected Lieberman again in the general election. But he won because of large majorities among independents and Republicans. That was made possible only because the Republicans, anticipating that Lieberman would be the Democratic candidate, nominated a nonentity who wound up getting less than 10 percent of the vote.

Six years later, Lieberman knows he would have no chance in a Democratic primary, since most of those Democrats who backed him in the past still hold his support for Republican John McCain in the 2008 presidential election against him. Virtually any Democrat could beat him. And he is still too much of a liberal on domestic policy to have a chance to win a Republican primary should he choose to try that route. That leaves him with the option of a straightforward run as an independent. But while Connecticut has a tradition of backing party-jumping mavericks in statewide races, the only way he can win is if he is able to claim, as he did in 2006, the lion’s share of Republican ballots. A McMahon candidacy will mean a well-funded and serious GOP candidate who is conservative enough to retain the loyalty of most of that party’s voters in November. That means Lieberman has no reasonable scenario for victory in 2012.

This makes it all but certain that the Congress that convenes in January will be the last in which Lieberman will sit. If so, it will be yet another indication that the Scoop Jackson Democrat — liberals on domestic policy and hawks on foreign policy — is truly extinct. Lieberman will, of course, be remembered as the man who came within a few hanging chads of being elected the first Jewish vice president of the United States. But his real legacy will be the fact that he was willing to risk his career for the sake of principle as he bucked his party’s loyalists by faithfully supporting the war against Islamist terrorists in Iraq.