Senate negotiators have agreed to empower the US to significantly restrict illegal migrant crossings at the southern border, according to sources familiar with the matter, a move aimed at ending the migrant surge that has overrun federal authorities over the past several months. The Senate deal, which is expected to be unveiled as soon as next week, would also speed up the asylum process to consider cases within six months – compared with the current system, under which it could take up to 10 years for asylum seekers. The details provide a new window into high-profile negotiations that have been...