The House of Representatives narrowly approved a Senate budget proposal on Thursday, paving the way for the long-anticipated tax reform package Republicans hope to pass by the end of the year.

The vote frees Republicans to pass a tax reform plan without needing 60 votes in the Senate, allowing them to potentially push it through on a party-line vote. The budget authorizes Congressional tax-writing committees to use the authorization process to tackle tax reform, removing the need for a supermajority and allowing Congress to push it through with 50 Republican votes. But the 216-212 margin by which the budget passed underscores how tricky threading the needle on tax reform will be for the GOP Congress, which must put together a package fiscally responsible enough to satisfy conservatives in the House without spooking moderates in the Senate.