Sen. Marco Rubio (R-Fla.) could complicate things for the Republicans as they try to pass their tax overhaul, having told reporters on Thursday he won’t support the legislation unless it increases the refundable portion of the child tax credit. Senate and House Republicans say they have reached an agreement on a tax bill, which lowers the corporate tax rate to 21 percent and top individual tax rate from 39.6 to 37 percent, and are just ironing out the final details. As it stands now, the bill sets the child tax credit at $2,000 per child, and Rubio wants it to be refundable against both payroll and income taxes. He “can’t in good conscience support” the legislation unless this happens, Rubio said, adding, “There’s a way to do it, and we’ll be very reasonable.” The GOP can only afford to lose two votes in the Senate.