Sen. Marco Rubio (R-FL) is planning to vote against the Republican tax bill unless the child tax credit is expanded.

Rubio, along with Sen. Mike Lee (R-UT), has been pushing hard for a larger child tax credit for weeks, but GOP leadership opposed their plan and it was voted down in the most recent version of the bill.

According to a report by the Washington Post, Rubio informed Senate GOP leadership of his plan today, and has been negotiating with Sen. Tim Scott (R-SC), who has been tapped to help reconcile differences between the House and Senate versions of the bill.

Currently, Republicans control 52 out of the 100 seats in the Senate, meaning they must have at least 50 Senators on board in order to pass the bill. (In the case of a tie, Vice President Mike Pence would cast the tiebreaker vote, and has given no indication he would not support the bill).

As I noted yesterday at RedState, the election of Democrat Doug Jones to the Alabama Senate seat has put pressure on Congressional Republicans to get the tax bill passed before Jones is sworn into office at the end of the month. Once that happens, just one Republican defector will be enough to kill the bill.

With the rapidly approaching Christmas holidays and the need to pass the bill through both the House and the Senate, there are only a few days remaining, and barely one day left to resolve this in the Senate and still expect to finish in time.

Sen. Bob Corker (R-TN) already has said he opposes the bill due to its effect on the federal deficit. A spokesman for Lee told the Washington Post that the Utah Senator is still undecided. If Lee joins Rubio, that will be enough to hold the bill hostage.

Essentially, the Rubio-Lee plan would expand the child tax credit to allow millions of families to claim the credit who pay payroll taxes even if they don’t earn enough to pay income taxes. They planned to pay for this increased credit by slightly shrinking the tax bill’s proposed cut to the corporate tax rate. Currently, the corporate tax rate is 35 percent, and the bill cuts that to 20 percent. The Rubio-Lee plan would trim that slightly, cutting it to 21 percent.

Senate leadership seems to be amenable to some expansion, but not as large a scale as Rubio wanted. The latest version of the bill increases the child tax credit to $2,000 per child, up from the current $1,000.

I’m on the email list for Rubio’s Senate office, and they have been sending out press releases on a seemingly daily basis pushing his child tax credit plan, and his social media feed is full of content promoting it as well. A significant amount of the criticism of the GOP tax bill has been that it offers too generous tax cuts to the upper brackets, while not doing enough for the working class. Rubio, along with Lee, are at least attempting to address that.

A Slap in the Face to Families | National Review – https://t.co/4DJhh8yepQ https://t.co/22YLsULbyj

— Marco Rubio (@marcorubio) December 13, 2017

20.94% Corp. rate to pay for tax cut for working family making $40k was anti-growth but 21% to cut tax for couples making $1million is fine?

— Marco Rubio (@marcorubio) December 12, 2017

Rubio deserves credit for fighting for this child tax credit he has spent so much energy promoting, and he’ll come out of this looking like he fought for working families as long as he either successfully gets the expanded child tax credit he wants, or follows through and votes against the bill.

Follow Sarah Rumpf on Twitter: @rumpfshaker.

This post has been cross-posted at RedState.