To further assist in carrying out the purposes of this subchapter, the Administrator may make financial contributions to the States (including interstate emergency preparedness authorities established pursuant to section 5196(h) of this title) for necessary and essential State and local emergency preparedness personnel and administrative expenses, on the basis of approved plans (which shall be consistent with the Federal emergency response plans for emergency preparedness) for the emergency preparedness of the States. The financial contributions to the States under this section may not exceed one-half of the total cost of such necessary and essential State and local emergency preparedness personnel and administrative expenses.