Sen. Susan Collins, R-Maine, said she opposes Republican proposals to reduce the income tax rate for millionaires and to eliminate the federal estate tax.

Speaking to Bloomberg on Monday, Collins said she might be open to adjusting upward the current threshold for triggering the estate tax but said “I don’t think there’s any need to eliminate the estate tax.” Collins, a moderate Republican, said the current threshold of $5.49 million for individuals means most small businesses and farms are exempt from having to pay the tax when the estate is passed down to heirs.

Collins also said she has shared with Republican leaders her concerns about lowering the income tax on people earning more than $1 million a year. Maine’s senior senator could play a crucial role in attempts to pass a tax reform passage because Republicans cannot afford to lose more than two caucus votes. Several other senators have also expressed concerns about the current proposal.

“I hope very much to be able to support a tax reform package,” Collins told Bloomberg. “It’s very difficult – I’m not going to say I can guarantee that because I don’t know what’s going to be in it.”