When the Senate voted, for the first time, to approve the stimulus, the vote was close. 61 Senators voted in favor of the bill, just one more than needed to approve cloture and end debate. When the package comes up for a final vote later today, the margin will almost certainly be even closer.
Sen. Ted Kennedy (D-Mass.) made it to the vote the first time around, but due to his illness, he won't be making it to the Senate tonight. And Sen. Sherrod Brown (D-Ohio) is back in his home state, attending a memorial service for his mother, who died last week. Brown may not be able to get back to Washington until 8 p.m., NBC's First Read reports. That means he'll probably be an hour late. Because of Kennedy's absence, Brown's vote is crucial, so Majority Leader Harry Reid will probably have to hold the vote open until the Ohio senator arrives.
Even then, with a margin this thin, there's reason for Reid to worry. Reportedly, none of the three Republicans who've crossed the aisle for the stimulus wanted to be the deciding vote during the last vote, so there's always the chance, though a very slim one, that someone will get cold feet.