With just a few days left before June ends, there's a clear frontrunner for the month's least surprising political development -- the endorsement Barack Obama received today from the AFL-CIO.

The massive conglomeration of 56 national and international unions -- comprising about 10.5 million workers -- steered clear of making a pick during the primary season because there was no consensus choice among the group's various affiliates. Many of the unions backed Obama, many supported Hillary Clinton and (while he was in the race) some were for John Edwards.

Once Obama emerged triumphant, though, it was a foregone conclusion the federation would get in his corner. And it's the clout the group's increasingly sophisticated political operation will add to his side that makes the endorsement, though predictable, noteworthy.

The days are long gone when union members voted in virtual lockstep with their leaders. But over recent campaign cycles, the federation has gotten better and better at marshaling its manpower and money to aid its favored candidates. Its get-out-the-vote efforts, for instance, played an important role in fueling the strong Democratic showing in the 2006 midterm elections. ... (LATimes)