Trump's drive to overhaul the U.S. tax code cleared a critical hurdle on Thursday when the Senate approved a budget measure that will allow Republicans to pursue a tax-cut package without Democratic support.

But Republicans, who control both the Senate and House of Representatives, have yet to produce a tax reform bill as a self-imposed deadline to overhaul the U.S. tax code by the end of the year approaches. The party's lawmakers differ widely on what cuts to make and how to pay for them.

They are under intense pressure to succeed on tax reform after failing so far to make good on their other main legislative ambition: scrapping Obamacare, the signature healthcare law of former President Barack Obama.