A marathon voting session on President Donald Trump’s sweeping domestic policy bill is underway in the Senate and has stretched overnight into Tuesday after a weekend of negotiations and delays.

With Sens. Rand Paul and Thom Tillis opposed to the package, GOP leaders can afford only one more defection. And multiple Republicans aren't yet sold on the measure.

After a late shift by Senator Lisa Murkowski to yes, the legislation now returns to the House, where its passage remains far from certain.