As has been said many times in this forum, you've got to have the "right to work" in the US before any reputable US company will hire you. There is no need for US companies to sponsor foriegn pilots when there are adequate numbers of experience US pilots to choose from. There is no pilot shortage, just a decrease in the experienced pilot pool. Some regionals are hiring inexperienced pilots with only 1000 hours total time and perhaps as few as 200 multi-eng hours, but probably not the ones you'd like to work for.