>PORTLAND, Maine — Some labor unions that helped U.S. Sen. Susan Collins win in 2014 say it’s too early to decide whether they’ll support her again in 2020 as her Democratic opponents courted workers over the Labor Day weekend. Collins, a Republican, was supported by several labor unions in her last re-election race. Her campaign touted the endorsements heavily, and they were notable because unions typically support Democrats, though her race was uncompetitive and she won with two-thirds of votes. Things could be different in 2020. Collins’ seat is expected the subject of one of the most expensive Senate campaigns...