The House easily passed a $78 billion bipartisan tax package on Wednesday after days of tensions within the GOP, but it's already showing signs of trouble in the Senate.

Why it matters: The deal left House GOP leadership scrambling to appease various factions' grievances about the measure, and ultimately passed with the help of Democrats.

• In the eleventh-hour, GOP leadership provided assurances to moderate GOP New Yorkers that a fix for the state and local tax deduction would see action in the House.
• Conservatives who voted against the measure blasted it for being brought up on suspension of the rules and argued it provided tax relief to undocumented immigrants — an allegation House Ways and Means Chair Jason Smith (R-Mo.) said was not true.

Zoom in: Proponents of the bill by Senate Finance Committee Chair Ron Wyden (D-Ore.) and Smith argued it's pro-growth and would provide a substantial win for lawmakers to campaign on back in their districts.

• The bill would primarily expand the Child Tax Credit and alter research & development (R&D) expensing for businesses to allow for immediate expensing.
• It would also end the Employee Retention Tax Credit Program and increase the Low-Income Housing Tax Credit.

The big picture: While the deal made it out of the House, it faces hurdles in the upper chamber as key senators say they won't support it in its current form.

• "That could be regular order through the Senate Finance Committee or maybe there's a way of having an amendment process on the floor," Senate Minority Whip John Thune (R-S.D.) said.
• Sen. Chuck Grassley (R-Iowa), a former chair of the Senate Finance Committee, appeared to say the quiet part out loud on Wednesday when he suggested presidential politics would play a role in the bill's fate.
• "Passing a tax bill that makes the president look good — mailing out checks before the election — means he could be re-elected, and then we won't extend the 2017 tax cuts," Grassley told reporters, incorrectly characterizing the child tax credit provision as a mailed check.