Failed drug vote points to bigger challenges for Democrats

The defection of three moderate House Democrats on drug pricing legislation highlights the steep challenge the party faces in pushing their $3.5 trillion package through Congress.

With thin margins in both the House and Senate, there are a range of tough issues that Democratic leaders must navigate, from the overall size of the measure to how to raise the taxes needed to pay for it.

Any one of those issues has the potential to take the entire package down in a House where Democrats can afford just three defections given unified GOP opposition.