FILE PHOTO: Senator Mike Lee (R-UT) walks to the Senate floor on Capitol Hill in Washington, U.S., July 27, 2017. REUTERS/Aaron P. Bernstein

WASHINGTON (Reuters) - U.S. Republican Senator Mike Lee has not decided whether to support a Republican tax bill and wants changes to the child tax credit, an aide to the lawmaker said on Thursday.

Both Lee and Republican Senator Marco Rubio want more of the proposed child tax credit to be refundable, Conn Carroll, Lee’s communications director said, adding Lee is “undecided on the tax bill as currently written.”

The sweeping tax bill needs a simple majority to pass in the Senate, in which Republicans hold 52 of the 100 seats and no Democrats are expected to support it.