There will most likely be some discussion before a tax proposal becomes a tax law.
There may be a heavy impact from a new tax law on charities making it less likely that people will donate to them, according to Reuters in "New U.S. law could curb charitable donations."
The Senate and the House of Representatives have both passed their own version of a tax reform bill but they remain far apart and negotiations are likely.
One thing the final bill might do is double the standard tax deduction people can take instead of itemizing their deductions. That would make it less likely that people will give to charities at the end of the year to lower their tax bills.
The other worry for charities is the gradual repeal of the estate tax that has been proposed.
Wealthy people often give to charities as a way to shrink the size of their estates to avoid the tax. If that is the sole motivation for giving, then charities could lose out.
Reference: Reuters (Nov. 30, 2017) "New U.S. law could curb charitable donations."