John Brunner 
World Swappers [EPUB ebook] 

The inhabited galaxy was caught in the crushing vice of a struggle for power. The political titans of the planets of mankind were making their bids for supremacy. The contestants: Cornice, man of strange powers, authority in the spheres of the intellect; and Bassett, man of money-power, financial and business wizard. As the association of human worlds drew near the teetering edge of internal revolutions; one of these men would be in a position to triumph. The only thing that neither side could foresee was that there were Others hovering among the stars, loo ling for new worlds to conquer!(First published 1959)