A potential stumbling block for the Republican tax bill was removed Friday afternoon when Sen. Marco Rubio, R-Fla., announced he would support the measure. Rubio had threatened to vote "no" on the bill, to win a more generous child tax credit for working families.

Another holdout, Sen. Bob Corker, R-Tenn., also announced his support Friday, putting the bill on a path toward likely passage in time for President Trump to sign the measure by Christmas.

Corker was the only Republican to vote against the Senate version of the tax bill. He said he changed his mind after "great thought and consideration."

"I believe that this once-in-a-generation opportunity to make U.S. businesses domestically more productive and internationally more competitive is one we should not miss," Corker said in a statement.

The bill would sharply reduce the corporate tax rate from 35 to 21 percent, potentially boosting jobs and wages. The measure also reduces individual taxes temporarily and creates a lower tax rate for so-called pass-through businesses such as partnerships.

The tax cuts are expected to take a big bite out of government revenue. Even after accounting for somewhat faster economic growth, congressional forecasters say the measure will add about $1 trillion to the federal deficit over the next decade.

Congressional Democrats are united in their opposition to the tax bill. They argue that it's overly tilted to the rich, with the bulk of the savings going to the top 1 percent of the income ladder by 2027.

In negotiations between the House and Senate, lawmakers agreed to a slightly higher corporate tax rate than Republicans initially wanted: 21 percent instead of 20 percent. They also lowered the top individual tax rate to 37 percent.

Cuts to that top rate frustrated Rubio, who argued lawmakers were again favoring the wealthy at the expense of working parents.

"For far too long, Washington has ignored and left behind the American working class," Rubio tweeted.

After he threatened to withhold his support for the bill, colleagues agreed to sweeten the child tax credit, which Rubio called "a solid step towards broader reforms which are both Pro-Growth and Pro-Worker."

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