Why do we need a new border deal? We have a border. It's illegal to cross that border anywhere but the established points of entry.
That is false. Individuals seeking asylum are able to request it regardless of where they enter the US. This is longstanding federal law and it's confusing how frequently conservatives try and spread falsehoods about it. Trump even lost several court cases making this absurd claim!
The federal government is responsible for defending the border and preventing illegal entry. No new legislation is necessary. The laws and duty's are clearly established, all that needs to happen is for the federal government to do their job.
Those administering the federal government say the resources provided are insufficient to do the job in a timely and effective manner.
Imagine having a police department of one person and then passing all sorts of laws to make things illegal. Then you say 'those are already illegal, our town sheriff just needs to do his job and arrest everyone.' All this of course ignores the fact that our immigration legislation as it is is awful and we need to make it much, much easier to legally immigrate to the US, which would require new legislation.
The problem is that Republicans affirmatively do not want to resolve the immigration situation, which is why they keep torpedoing every attempt to do so. The problem you're complaining about? Republicans LOVE it and want it to continue forever. If you want to solve it, vote for Democrats.