A new poll from Newsweek has some interesting data on Hillary Clinton’s electability. According to the poll, Hillary beats John McCain 50 to 43 percent, squeaks by Rudy Giuliani 48 to 47 percent and trounces Mitt Romney, 58 to 32 percent. Her presumptive rival, Barack Obama, narrowly loses to McCain and Giuliani but thumps Romney as well, 55 to 25 percent.

It’s important to take this poll, and every other one you’ll see until Labor Day, with a grain of salt. Remember when Joe Lieberman was atop the ’04 field? Or Howard Dean was at 1 percent? The public knows very little about candidates like Obama and Romney. No one can predict exactly how a Hillary candidacy will play or whether Obama can live up to the hype.

That said, Hillary’s lead over McCain is interesting because of what it says about him. In previous polls the Senator from Arizona has handily defeated his Democratic opponents. But in recent months his numbers have begun to fall. Among independent voters, he’s slipped 15 points since March.

Even McCain admits that only 15 to 18 percent of Americans support his plan to escalate the war in Iraq by sending more troops. Once more Americans learn about his dogged support for the war–and busy courtship of the religious right–they may form a different opinion of the so-called maverick.