Florida Sen. Marco Rubio warned Friday that there are "going to be problems" if the tax bill conference committee settles for a corporate tax rate higher than 20 percent without including his child tax credit proposal in the bill.

The Republican was rebuffed last week in his attempt to amend the Senate tax cut bill to set the corporate rate at 20.94 percent in exchange for making the $2,000 child tax credit available to more low-income families.

Rubio then criticized the stance that the 20 percent corporate rate goal could not be tweaked to pay for making the credit refundable against payroll taxes.

Over the weekend, however, President Trump suggested that he would settle for a rate higher than 20 percent. Since then, there have been rumblings that Congress might shoot for a rate of 22 percent to meet other targets for the bill without exceeding the $1.5 trillion limit on the total tax cut.

Although Rubio's amendment failed, he did vote for the underlying bill.

As one of just 51 "yes" votes for the tax bill, Rubio is almost certainly a must-have for Majority Leader Mitch McConnell to be able to pass the conference bill.