washington president donald trump drive win passage sweep republican tax bill u.s. congress hit potential obstacles thursday two republican senators insist change join list lawmakers whose support uncertain florida marco rubio former presidential contender tell reporters capitol hill bill propose refundability taxpayers child tax credit expand ... high 1,100 rubio mike lee utah talk senators expand child tax credit refundability say conn carroll lee spokesman lee undecided tax bill currently write carroll say telephone interview child tax credit u.s. tax code mean low tax bill work families children fast-moving republican tax package evolve tilt increasingly toward benefit businesses wealthy taxpayers trend aid say privately grow concern lawmakers provision offset revenue cost last-minute change also become worrisomely unclear say resist demand weeks cut top income tax rate rich taxpayers bill author agree recent days low 37 percent 39.6 percent concern find money low top rate ... find little bite least somewhat increase refundable portion child credit rubio say white house spokeswoman sarah sanders say white house continue work rubio child tax credit headline feature bill deep cut 21 percent 35 percent corporate income tax rate step corporate tax lobbyists pursue many years orrin hatch chairman senate tax committee one bill chief author say senate would probably vote final senate-house measure monday say hop rubio concern could address important us hatch say know leadership want problem question senate approve wide-ranging tax bill dec. vote 51-49. senator bob corker republican join 46 senate democrats two independents vote bill early house representatives approve tax legislation recent days negotiators chamber scramble reconcile two bill change specific part fly lock enough vote pass trump say want final bill desk enactment christmas enact bill would first major legislative achievement trump republicans since take office january corker lead republican fiscal hawk reiterate concern bill expansion federal deficit address independent nonpartisan tax analysts estimate bill expand 20 trillion national debt least trillion next 10 years moderate senator susan collins also non-committal bill part concern provision repeal obamacare federal fine impose americans buy health insurance senate vote outlook muddle senator john mccain admission hospital treatment side effect cancer therapy office say look forward return work soon possible carroll say child tax credit make fully refundable would cost billion lose revenues 10 years lee rubio want expand refundability current law maximum child tax credit 1,000 per eligible child 17 allow portion family earn current form legislation expand credit lee rubio seek help families especially lower-income bracket two senators fail effort senate floor tax bill initially debate republicans 52-vote senate majority lose two vote still win approval vice president mike pence able vote break tie pence delay plan trip middle east case vote need final tax bill republican tax vote near senators waver