As his poll number continue to drop and reelection hopes dim, Donald Trump is again weaponizing US immigration policy to energize his most aggressive, anti-immigrant voter base.  He is expected to sign an executive order on Monday that would suspend temporary visas for foreign workers until the end of 2020, infuriating US business and industry groups who rely on foreign talent.  The freeze will apply to H-1B visas designed for high-skilled workers, particularly in the tech industry, and H-2B visas used by seasonal workers, such as in the construction and hospitality industries.