Yesterday during a conference call with reporters, Sen. Hillary Clinton's chief strategist Mark Penn said that Sen. Barack Obama was unelectable.

The Pennsylvania vote, he said, will be a "very significant test of who could really win the general election."

"We believe this will show Hillary is ready to win, and that Senator Obama really can't win the general election," Penn said.

The Obama camp was quick to reply, sending out an e-mail late last night debunking the comments made by Penn.

"It can't inspire too much confidence in the Clinton campaign when their pollster ignores both polls and math by making comments as divorced from reality as this one. Senator Obama is leading in delegates, states won, the popular vote, and fares better than Senator Clinton against John McCain in poll after poll, including critical swing states like Iowa, Colorado, Pennsylvania, New Mexico and Wisconsin."

Jonathan Chait at The New Republic says in "The Plank" blog that Penn's comments are part of the Clinton campaign's strategy to convince superdelegates that they need to support Clinton if they want to win in the fall. Chait says in one way it's a silly argument.

"There's not even good evidence to suggest that Obama is less likely than Clinton to win the general, he writes. "Currently, the [Real Clear Politics] poll average has both defeating John McCain by an average of 1.5%. Before the last couple weeks, when McCain and Clinton have both been making mutually-reinforcing attacks on Obama nearly every day, Obama was running well ahead of Clinton in those head-to-head matchups."

But that doesn't mean the strategy won't work. Chait says Clinton needs the superdelegates to break 2-1 in her favor and the only way she can do that is by repeating 'he can't be elected.'

"Some people have treated this as an unfortunate byproduct of Clinton's decision to continue her campaign. It's actually a central element of the strategy. Penn is already saying he's unelectable. It's not true, but by the time the convention rolls around, it may well be."