Joe Lieberman's endorsement of John McCain will, of course, only further serve to underscore liberals' deep, deep doubts about the "independent Democrat" from Connecticut. At the same time, I worry if it won't underscore conservatives' doubts about McCain as well. Nobody, after all, really doubts McCain's commitment to a hawkish foreign policy -- he was Bill Kristol's choice in 2000 for a reason -- and that's all Lieberman's endorsement really signifies. After all, Republican primary voters aren't going to be attracted to the other things Lieberman could praise McCain for: his reasonable-for-a-Republican stance on global warming or zeal for certain forms of campaign finance restrictions and general habits of party disloyalty.
This does, however, seem to me like something of a blow to Rudy Giuliani's credibility. After all, Giuliani is closer to Lieberman on several issues than is McCain -- abortion, guns, gays, etc. And Rudy's running as the ultimate hawk, the rock-solid guy on the one set of issues where Lieberman has really distinguished himself by staking out a far-right position. But Lieberman's not buying it. As a consummate hawk, he sees a kindred spirit in McCain and presumably recognizes that Rudy's brand of militarism is a kind of clown show; not insincere, but totally uninformed by any knowledge of the issues or the landscape whatsoever.
Matthew Yglesias is a former writer and editor at The Atlantic.