(CNN) - Republicans have celebrated since Saturday the passage of their tax bill through the Senate, but on Monday night some key GOP members were thinking of another measure -- one to keep the federal government funded -- when they threatened to vote against a routine step to send the tax plan to a conference committee.
Senate Republicans passed their tax bill in the early hours of Saturday morning and now Republicans across the Capitol are bracing themselves for their next challenge: conference -- and even that step looked at least for a few moments Monday evening to be in jeopardy.
The House of Representatives formally voted 222-192 Monday night to go to conference committee on the tax bill, where it will work to iron out key differences between its bill and the Senate's. The House later Monday evening appointed the conferees, the select lawmakers tasked with trying to deliver the reconciled tax bill to President Donald Trump's desk before Christmas.
The office of House Speaker Paul Ryan, R-Wisconsin, said he had named as conferees GOP Reps. Kevin Brady of Texas, Devin Nunes of California, Peter Roskam of Illinois, Diane Black of Tennessee, Kristi Noem of South Dakota, Rob Bishop of Utah, Don Young of Alaska, Greg Walden of Oregon and John Shimkus of Illinois.
House Minority Leader Nancy Pelosi, D-California, announced her choices as Democratic Reps. Richard Neal of Massachusetts, Sander Levin of Michigan, Lloyd Doggett of Texas, Raúl Grijalva of Arizona and Kathy Castor of Florida.
There had been some unexpected drama earlier on what was a routine vote. The vote was tied for a period as some Republicans made a show of their displeasure with plans to implement a two-week continuing resolution to fund the government beyond the current deadline scheduled for Friday.
Republican leaders have said their plan will extend government funding until December 22, while some members of the conservative House Freedom Caucus wanted to keep funding going until the end of December so as not to vote right before Christmas. After some negotiating, several members changed their votes to yeses, which allowed the bill to pass, though no apparent promises have been made to Freedom Caucus members. Other Republicans were livid with the caucus, with Rep. Tom Rooney of Florida saying he had no idea how you would vote against going to conference on a tax bill you just supported.
Republicans have a big job ahead of them as major differences remain between the Senate and House tax bills. For one, the Senate bill repeals the individual mandate, which requires individuals to buy health insurance or face a fine. The House bill did not repeal it. The Senate bill also kept intact the alternative minimum tax, which the House repealed. The Senate also sunset tax cuts for individuals, something the House bill kept permanent.
The broad contours of the two bills remain the same, but the regional differences that complicated the tax bill as it moved through the House and Senate are also likely to pop up again in conference. For example, northeast and California Republicans have advocated to restore more state and local tax deductions than are currently in the two chambers' bills. And Republicans in both the House and Senate have argued that larger tax breaks should be given to so-called pass through businesses.
Most of the work of the conference committee will happen in private negotiations between leadership and committee staff as they tackle one of the most challenging aspects of the negotiations: ensuring that the bill meets special Senate rules. Under reconciliation -- the process that gives Republicans the ability to pass their bill with just 51 votes in the Senate -- Republicans cannot produce a bill that adds to the deficit after 10 years.
Senate Majority Leader Mitch McConnell will also appoint conferees. The Senate is expected to vote to go to conference later this week.
This story has been updated and will continue to update with additional developments.