CUPE leader Sid Ryan's anti-Israeli ravings serve to remind us how important the existence of the NDP is to the Liberals.
After all, if the NDP wasn't around and if we had a two party system, Conservative vs. Liberal, then Ryan would likely be a supporter of the Liberal Party, just as union bosses in the United States support the Democratic Party.
And if that were the case, just imagine how embarrassing it would be for Liberal leader Michael Ignatieff to have a looney-tunes, loose cannon like Ryan in his camp.
That's why it's lucky for the Liberals that the NDP is around to attract Ryan and other wacky leftists.
The NDP, in other words, is like a holding tank for the Liberals; they can keep their distance from the NDP's radical elements, but they can also dip into it whenever they are in need of "progressive" votes.