bret: good evening. i m bret baier. president joe biden vacations in the caribbean as republican presidential candidates return to the campaign trail. police in texas investigate the deaths of a pregnant teenager and her boyfriend in what they call a perplexing case. and doctors are warning about a tripledemic this winter as a new covid strain spreads throughout the united states. dr. marc siegel joins us to discuss. but, first, breaking tonight, another massive group of migrants is making its way through mexico as immigration officials work to process the thousands already waiting at the border. many of those who have been allowed to enter the u.s. are being sent further north where local officials say president joe biden and his administration have ignored their pleas for additional assistance. the president, meanwhile, is heading south to the caribbean for vacation as his top cabinet officials meet with mexico s president to discuss the crisis. we have fox team coverag