A month ago U.S. Rep. Fred Upton, who represents the 6th District encompassing Kalamazoo and a large swath of Southwest Michigan, voted for the Infrastructure Investment and Jobs Act. After that, a flood of phone calls rushed into Upton’s office — more than 1,000 in a matter of days. There were death threats and threats to Upton’s family and staff — a whirlwind of profanity-laced tirades rooted in a political environment more toxic than anything Upton said he’s seen in his 35 years in Congress.