Can Trump assume emergency powers to deal with the invasion at our southern border?

it seems quite clear you are not familiar with the National Emergencies Act of 1975.

§ 1705. Allocation of funds.

For the purposes of carrying out the provisions of this subchapter and subchapters II and III of this chapter the President, in his discretion, is authorized to provide such funds or any portion thereof by allotment to the Secretary from any funds that are available, or may hereafter be made available, to the President for emergency purposes.

JWK

What will?

Oh yes there is.

Why would any nation bother to use an army to invade us if they can just send unarmed civilians to invade us unopposed??

The US Constitution is the supreme law of the land, Not the National Emergencies Act. I believe that the National Emergencies Act is itself Unconstitutional.

What is the basis for this opinion and can you see a way for the house to overcome this ruling?

To a certain degree I agree with you. I detest any president being able to exercise unlimited power. But, there are times when a president must exercise extraordinary power to be in compliance with our Constitution, which he took an oath to uphold. And when taking his oath our president, by the terms of our Constitution, is obligated to “repel invasions” which may require an immediate action. Also, keep in mind what our Constitution states in crystal clear language:

“The Privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it.”

Of course, the President in taking emergency actions, if such actions are not agreeable to Congress, then Congress has the obligation to adopt a joint resolution calling an end to the “emergency”.

So, Congress is free to call an end to the President’s declared “emergency” and forbid the building of a wall intended to “repel an ongoing invasion”. And, this is how our Constitution works.

JWK