Maine Sen. Olympia Snowe is expected to be the swing vote today on a large package of tax cuts being considered by the U.S. Senate Finance Committee.

There are 11 Republicans on the committee and nine Democrats. Everyone except Snowe has made their position known. Democrats have said they will oppose the legislation, which extends through 2010 tax breaks on dividends and capital gains that were passed in 2001 and 2003, and the other 10 Republicans have said they will support it.

It’s unconscionable to extend about $21 billion in tax cuts that benefit primarily the wealthiest at the same time that the Congress is trying to cut as much as $54 million from programs that serve the poor and middle class, including college student loans.

Snowe voted against the Senate version of the budget cuts, which would eliminate $36 billion in funding for programs such as Medicaid, partly because it did not include $3 billion to protect low-income families this winter against the rising cost of heating oil.

Snowe’s Republican colleagues are trying to ply her with a tax credit that would help some people with their heating bills. But the families in most desperate need of assistance wouldn’t be helped by a tax credit; they don’t make enough to have any federal tax liability.

Snowe has tremendous power to shape the tax package. It falls to her to restore fiscal discipline to the Finance Committee and to the Senate.