Because Claire McCaskill indicates openness to retaining them, at least for taxpayers in the under $1 million range. (President Obama wants taxes to rise on individuals reporting over $200,000.)
From The Hill in June:
Sens. Claire McCaskill (Mo.) and Bill Nelson (Fla.), two Democrats facing tough races this year, on Thursday declined to rule out support for an across-the-board extension of the rates.
“If you want to do something in the spirit of compromise, you don’t start out by saying, ‘I refuse to do this’ or ‘I refuse to do that,’ ” said McCaskill. “It’s not my preference to extend tax cuts to multimillionaires — that’s not my preference — but I want to keep every option open in the spirit of compromise.”
Those words raise the curtain on what politics after 2012 will look like: a re-elected President Obama will likely face a House and Senate much more conservative than he is, even if the Senate is still headed by a Democratic majority.