There was an immigration bill on the house floor roughly 10 days ago - it failed. . . .
The US (as do most countries) already has the power, ability, right, and laws to control its own borders. It isn't enforcing those laws or using that power, ability, or right. Also, it has put in place incentives that encourage people to illegally cross the border.
Which results in this:
So, the immigration bill you talk about first isn't necessary to enforce the border. But also it had LOTS of OTHER stuff in it. That's what happens with bills. It might have something good in it -- plus 10 lbs of poison. You vote against it. Partisans and the naive then point tremulous fingers at you: "You voted against the good thing!!!!!!"