These are the GOP senators that could take down the Republican tax bill

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President Donald Trump and Senate Majority Leader Mitch McConnell

• Senate Republican leaders want to pass their version of the Tax Cuts and Jobs Act (TCJA) by the end of the week.
• There are a slew of Republicans, however, who still have serious concerns about the bill.
• GOP leaders can only afford to lose two votes for the TCJA to pass.

The Republican tax plan is in the midst of a critical week in the Senate, but it's unclear if GOP leaders have the votes to pass their ambitious package.

Senate Majority Leader Mitch McConnell and Republican leaders say they want to bring the Tax Cuts and Jobs Act (TCJA) to the Senate floor for a vote by the end of the week. That would keep the TCJA on track to meet President Donald Trump's self-imposed Christmas deadline for final passage.

While leadership may have an ambitious timeline, a sizeable group of GOP senators have expressed concerns about the bill since its release just more than two weeks ago.

Their issues range from the tax legislation's treatment of small businesses, to healthcare, to the federal deficit. Since the bill can only lose two Republican votes for it to pass, the margin for error is incredibly thin.

Below we've collected the eight senators to watch in the next week and why they could spoil Republican leaders' best-laid plans.