Washington (CNN) The White House is moving forward with plans to shift existing federal funds to pay for construction of a wall on the southern border, a senior administration official and source close to the White House said.

But in the face of several lawsuits challenging Trump's authority to declare a national emergency to reallocate billions of dollars toward a border wall, the White House does not plan to spend any of the funds that hinge on Trump's national emergency declaration, a source close to the White House told CNN.

Instead, the White House plans to focus on building new portions of border wall using funds from the Defense Department's drug interdiction program and Treasury Department's asset forfeiture fund, which do not rely on the national emergency declaration. Those two sources of funding alone amount to $3.1 billion.

This will allow the White House to begin construction on new border barriers without risking an injunction tied to the national emergency declaration. And at the same time, the White House will be able to put its plans in motion to access the national emergency funds at a later date.

As of now, the plan is to wait until the Supreme Court rules on Trump's use of the national emergency declaration before using the controversial military construction funds that can only be accessed using the national emergency statute. The White House also knows it cannot possibly spend $8 billion in wall-funding over the next year, and so it plans to access those national emergency funds last.

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