Congress returns from its midsummer break Monday for a crucialthree-week stretch that will help determine whether PresidentDonald Trump can deliver on his promise of a historic tax cut.

Several obstacles await lawmakers, including the ongoinghealth-care fight, divisions among Republicans on the basicparameters of a tax bill, and a maelstrom of upcoming deadlines tokeep the government running and avert a catastrophic default onU.S. debt.

Republican leaders had hoped to spend July working on what HouseSpeaker Paul Ryan has called a once-in-a-generation bid to overhaulthe U.S. tax code. But the Senate remains bogged down with thepresident's call to undo Obamacare. With no clear endgame for thateffort, observers question the prospects for tax legislation, whichcan't move procedurally until health care is off the agenda.